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SB 431542

Catalog No.GC11545

SB 431542 Chemical Structure

SB-431542, a small molecule inhibitor

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10mM (in 1mL DMSO)
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Kinase experiment [1]:

Preparation Method

The kinase domain without the GS region was cloned and expressed as a GST fusion protein. Expressing the protein without the GS domain, which has been shown to regulate the kinase activity, creates a constitutively active kinase that is able to phosphorylate GST-Smad3. Test the effects of SB-431542 on ALK5 and ALK4 kinase activity with GST-Smad3 as substrate.

Reaction Conditions

The Kinase assays were performed with 65 nM GSTALK5 and 184 nM GST-Smad3 in 50 mM HEPES, 5 mM MgCl2, 1 mM CaCl2, 1 mM dithiothreitol, and 3 μM ATP. Reactions were incubated with 0.5 μCi of [33P]γATP for 3 h at 30°C.


SB-431542 is a selective ALK5 inhibitor with little activity against p38 MAPK. SB-431542 also inhibits ALK4 activity. Which is consistent with the degree of homology between these kinases, such that ALK4 is the closest related kinase to ALK5. This data clearly demonstrated that SB-431542 is a potent and selective inhibitor of ALK5 and ALK4, with slightly higher selectivity for ALK5.

Cell experiment [1]:

Cell lines

Renal proximal tubule epithelial cells (RPTEC)

Preparation Method

Cells were grown in Earle’s minimum essential medium supplemented with 10% fetal calf serum, penicillin (5 units/ml), and streptomycin (5 ng/ml). Cells were serum-starved for 24 h before treatment.

Reaction Conditions

Cells were treated with TGF-β1 (5 ng/ml) plus increasing concentrations of SB-431542 (50, 250, 500, and 700 nM).


SB-431542 could be used to evaluate whether ALK5 activity is required for TGF-β1-induced translocation of Smad3. SB-431542 at a concentration of 1 μM significantly reduced the TGF-β1-induced nuclear accumulation of Smad proteins. Thus, SB-431542 selectively inhibits TGF-β1–induced Smad translocation without affecting BMP-induced Smads.

Animal experiment [2]:

Animal models

Male Sprague-Dawley rats aged 5 weeks, weighing 200-220 g

Preparation Method

Rats lived in air served as control groups, and rats lived in an air condition incubator containing 10% O2 to simulate chronic hypoxia animal model, and served as model groups. Model groups were treated with daily intraperitoneal injections of the SB-431542 for 28 days.

Dosage form

10 mg/kg; 20 mg/kg


SB-431542 inhibited the proliferative activity as a function of exposure time and concentration. Treated rats with SB-431542 caused more pathological changes in vascular adventitia, and the severity of the changes varied from slight to moderate depending on concentrations. In addition, the pulmonary arteries in the hypoxia-induced model groups had greater amounts of collagen fibers than that of the control groups. In comparison, collagen fibers were significantly reduced after treatment with SB-431542 (P < 0.01).


[1]. Laping NJ, et al. Inhibition of transforming growth factor (TGF)-beta1-induced extracellular matrix with a novel inhibitor of the TGF-beta type I receptor kinase activity: SB-431542. Mol Pharmacol. 2002 Jul;62(1):58-64.

[2]. Yuan W, et al. SB-431542, a specific inhibitor of the TGF-β type I receptor inhibits hypoxia-induced proliferation of pulmonary artery adventitial fibroblasts. Pharmazie. 2016 Feb;71(2):94-100.


SB-431542, a small molecule inhibitor of the type I TGF-β receptor, blocks intracellular mediators of TGF-1 signaling, which leads to decreased TGF-β1–mediated proliferation, cytokines and collagen expression. In clinical settings, SB-431542 is widely used to treat respiratory asthma, and inhibits proliferation and synthesis of adventitial fibro in the process of pulmonary vascular remodeling.[1]

In vitro study indicated that SB-431542 is able to inhibit ALK5 with an IC50 of 94 nM and other type I receptors, such as ALK4. Although SB-431542 inhibited ALK4 with an IC50 of 140 nM. Moreover, SB-431542 inhibited TGF-β1–induced collagen Iα1 and PAI-1 mRNA with IC50 values of 60 and 50 nM, respectively. In addition, SB-431542 inhibited TGF-β1–induced fibronectin mRNA and protein with IC50 values of 62 and 22 nM, respectively. These data demonstrate for the first time that ALK5 activity is required for TGF-β1 regulation of extracellular matrix markers FN, collagen Iα1, and PAI-1 mRNA.[1]

In vivo study demonstrated that SB-431542 has the capacity to inhibit TGF-β1-induced gene expression. SB-431542 is recognized as a important inhibitor of the TGF-β1 receptors in blocking TGF-β1/Smads signal pathways in vascular remodeling. Moreover, hypoxia-induced vascular remodeling can significantly increase the amount of cytokines and collagen in vascular adventitia. However, after the treatment of SB-431542, attenuation of the fibrosis promoting effects of TGF-β1, including TGF-β1-induced cell proliferation, cell motility, cell migration and cell synthesis were observed. Therefore, it is significant to the identify the potential of SB-431542 for the treatment of hypoxia-induced pulmonary hypertension.[2]

[1]. Laping NJ, et al. Inhibition of transforming growth factor (TGF)-beta1-induced extracellular matrix with a novel inhibitor of the TGF-beta type I receptor kinase activity: SB-431542. Mol Pharmacol. 2002 Jul;62(1):58-64.
[2]. Yuan W, et al. SB-431542, a specific inhibitor of the TGF-β type I receptor inhibits hypoxia-induced proliferation of pulmonary artery adventitial fibroblasts. Pharmazie. 2016 Feb;71(2):94-100.

Chemical Properties

Cas No. 301836-41-9 SDF
Synonyms N/A
Chemical Name 4-[4-(1,3-benzodioxol-5-yl)-5-pyridin-2-yl-1H-imidazol-2-yl]benzamide
Canonical SMILES C1OC2=C(O1)C=C(C=C2)C3=C(NC(=N3)C4=CC=C(C=C4)C(=O)N)C5=CC=CC=N5
Formula C22H16N4O3 M.Wt 384.39
Solubility ≥ 19.2mg/mL in DMSO, ≥ 10.06 mg/mL in EtOH with ultrasonic Storage Store at -20°C
General tips For obtaining a higher solubility , please warm the tube at 37 ℃ and shake it in the ultrasonic bath for a while.Stock solution can be stored below -20℃ for several months.
Shipping Condition Evaluation sample solution : ship with blue ice
All other available size: ship with RT , or blue ice upon request

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Research Update

Sustained Delivery of SB-431542, a Type I Transforming Growth Factor Beta-1 Receptor Inhibitor, to Prevent Arthrofibrosis

Tissue Eng Part A2021 Nov;27(21-22):1411-1421.PMID: 33752445DOI: 10.1089/ten.TEA.2021.0029

Fibrosis of the knee is a common disorder resulting from an aberrant wound healing response and is characterized by extracellular matrix deposition, joint contraction, and scar tissue formation. The principal regulator of the fibrotic cascade is transforming growth factor beta-1 (TGF-β1), a factor that induces rapid proliferation and differentiation of resident fibroblasts. In this study, we demonstrate successful inhibition of TGF-β1-driven myofibroblastic differentiation in human fibroblast-like synoviocytes using a small molecule TGF-β1 receptor inhibitor, SB-431542. We also demonstrate successful encapsulation of SB-431542 in poly(D,L-lactide-co-glycolide) (PLGA) as a potential prophylactic treatment for arthrofibrosis and characterize drug release and bioactivity in a three-dimensional collagen gel contraction assay. We assessed the effects of TGF-β1 and SB-431542 on cell proliferation and viability in monolayer cultures. Opposing dose-dependent trends were observed in cell proliferation, which increased in TGF-β1-treated cultures and decreased in SB-431542-treated cultures relative to control (p < 0.05). SB-431542 was not cytotoxic at the concentrations studied (0-50 μM) and inhibited TGF-β1-induced collagen gel contraction in a dose-dependent manner. Specifically, TGF-β1-treated gels contracted to 18% ± 1% of their initial surface area, while gels treated with TGF-β1 and ≥10 μM SB-431542 showed no evidence of contraction (p < 0.0001). Upon removal of the compound, all gels contracted to control levels after 44 h in culture, necessitating sustained delivery for prolonged inhibition. To this end, SB-431542 was encapsulated in PLGA microspheres (SBMS) that had an average diameter of 87.5 ± 24 μm and a loading capacity of 4.3 μg SB-431542 per milligram of SBMS. Functional assessment of SBMS revealed sustained inhibition of TGF-β1-induced gel contraction as well as hallmark features of myofibroblastic differentiation, including α-smooth muscle actin expression and connective tissue growth factor production. These results suggest that SB-431542 may be used to counter TGF-β1-driven events in the fibrotic cascade in the knee cartilage. Impact statement Arthrofibrosis is the most prevalent comorbidity resulting from orthopedic procedures such as total knee arthroplasty that is characterized by excess deposition and accumulation of extracellular matrix. Despite its prevalence, treatments are generally palliative, and there is no effective prophylactic therapy. We report that the small molecule transforming growth factor beta-1 (TGF-β1) receptor inhibitor, SB-431542, can inhibit the TGF-β1-driven myofibroblastic differentiation of fibroblast-like synoviocytes. To provide sustained inhibition, we explored the use of SB-laden microspheres as a prophylactic therapy in a three-dimensional contraction model of fibrosis and propose that such therapies will have the potential to improve the standard of care for arthrofibrosis.

SB-431542 inhibition of scar formation after filtration surgery and its potential mechanism

Invest Ophthalmol Vis Sci2009 Apr;50(4):1698-706.PMID: 19098325DOI: 10.1167/iovs.08-1675

Purpose: To explore the inhibitive effect of SB-431542 (an ALK5 inhibitor) on scar formation after glaucoma surgery and to identify the potential pharmacologic target(s).
Methods: Twenty-four New Zealand rabbits underwent filtration surgery on the right eye and were divided into a control group and three experimental groups (n=6). Human Tenon's fibroblast monolayer was scraped to generate a single gap, and then the control medium with SB-431542 only or containing 10 microg/L TGF-beta1 and SB-431542 (1-20 microM) was added. The cells were pretreated with SB-431542 or in control medium for 30 minutes before induction with 10 microg/L TGF-beta1 or 1 microg/L TGF-beta2. The expression of alpha-SM-actin, CTGF, and Col I, as well as changes in the Smad, ERK, P38, and AKT signaling pathways were detected.
Results: In comparison with the control rabbits, the IOPs in the experimental groups remained at lower levels until day 25 (P<0.05) after the surgery. Histologic profiles showed that there was only a mild deposition of collagen in the subconjunctival space in the experimental groups. The cell growth and migration were inhibited effectively by SB-431542, regardless of whether TGF-beta was present in the culture system. SB-431542 abrogated TGF-beta-induced upregulation of alpha-SM-actin, CTGF, and Col I. It effectively inhibited the phosphorylation of Smad2 stimulated by TGF-beta but not that of the components of the MAPK pathways.
Conclusions: SB-431542 inhibits scar formation after glaucoma filtration surgery. The mechanism may be that SB-431542 interferes in the phosphorylation of Smad2, thus abrogating TGF-beta-induced fibroblast transdifferentiation and then decreasing Col I synthesis.

SB-431542 inhibits TGF-beta-induced contraction of collagen gel by normal and keloid fibroblasts

J Dermatol Sci2005 Jul;39(1):33-8.PMID: 15978417DOI: 10.1016/j.jdermsci.2005.01.013

Background: Transforming growth factor (TGF)-beta induces fibroblast contraction, which is implicated in wound healing and keloid formation. SB-431542 is a novel specific inhibitor of TGF-beta type I receptor kinase activity.
Objective: We sought to determine whether SB-431542 inhibited TGF-beta-induced fibroblast contraction.
Methods: We used an in vitro type I collagen gel contraction assay with normal or keloid dermal fibroblasts incorporated.
Results: TGF-beta induced contraction of collagen gels with normal dermal fibroblasts incorporated, which was efficiently suppressed by SB-431542. Keloid fibroblasts showed higher basal contraction of collagen gels in the absence of TGF-beta than normal fibroblasts, which was enhanced by addition of TGF-beta. SB-431542 suppressed both the basal and TGF-beta-enhanced contraction of collagen gels by keloid fibroblasts. These inhibitory effects of SB-431542 were associated with suppression of TGF-beta-induced alpha-smooth muscle actin (alpha-SMA) expression and phosphorylation of Smad2 in normal and keloid fibroblasts.
Conclusion: SB-431542 can suppress TGF-beta-induced contraction of collagen gel by normal and keloid dermal fibroblasts. Importantly, SB-431542 can inhibit basal contraction of collagen gel by keloid fibroblasts. These results suggest that an inhibitor of TGF-beta type I receptor kinase activity may have therapeutic potential for excessive skin contraction as observed in keloid.

SB-431542, a specific inhibitor of the TGF-β type I receptor inhibits hypoxia-induced proliferation of pulmonary artery adventitial fibroblasts

Pharmazie2016 Feb;71(2):94-100.PMID: 27004374DOI: 10.1128/AAC.00022-07

The vascular remodeling process plays an important role in the pathology of hypoxia-induced pulmonary hypertension, and it includes cell proliferation, cell motility, cell synthesis and collagen coagulation. Due to their proliferation and synthesis ability, the adventitial fibroblasts are thought to be critical in the vascular remodeling process initiated in response to hypoxia. However, the factors driving hypoxia-induced fibroblast proliferation and synthesis have yet to be elucidated, and the treatment regimens to treat hypoxia remain ineffective. As forthis study, its purpose was to examine the effects exerted by SB-431542, a small-molecule antagonist of transforming growth factor-β-receptor, on the proliferation, synthesis and collagen coagulation in cultured adventitial fibroblasts. Another aim of this study was to assess the inhibitory ability of SB-431542 on pulmonary vascular remodeling in chronic hypoxia in vivo.The cell morphology and proliferation of cultured adventitial fibroblasts was assessed by laser confocal microscopy and the MTT assay, respectively. Additionally, collagen synthesis was determined by hydroxyproline chromatography, while the expression of cytokines in adventitial fibroblasts and lung tissues was evaluated by immunohistochemical and reverse transcription PCR analyses. The results indicated that the exposure of cultured fibroblasts to 1% oxygen led to the up regulation of cell proliferation, cell synthesis. In addition, increased expression of cytokines and collagen was detected in vivo in the pulmonary artery adventitia of rats exposed to chronic hypoxia. Conversely, SB-431542 inhibited fibroblast proliferation and synthesis in the process of hypoxia-induced pulmonary hypertension (P < 0.01). Thus, the results suggested that by reducing cell proliferation, cell synthesis of vascular adventitia, small molecule inhibitors of the TGF-β1 receptors may offer a novel therapy for pulmonary hypertension.

SB-431542, a transforming growth factor beta inhibitor, impairs Trypanosoma cruzi infection in cardiomyocytes and parasite cycle completion

Antimicrob Agents Chemother2007 Aug;51(8):2905-10.PMID: 17526757DOI: 10.1128/AAC.00022-07

The antiinflammatory cytokine transforming growth factor beta (TGF-beta) plays an important role in Chagas disease, a parasitic infection caused by the protozoan Trypanosoma cruzi. In the present study, we show that SB-431542, an inhibitor of the TGF-beta type I receptor (ALK5), inhibits T. cruzi-induced activation of the TGF-beta pathway in epithelial cells and in cardiomyocytes. Further, we demonstrate that addition of SB-431542 greatly reduces cardiomyocyte invasion by T. cruzi. Finally, SB-431542 treatment significantly reduces the number of parasites per infected cell and trypomastigote differentiation and release. Taken together, these data further confirm the major role of the TGF-beta signaling pathway in both T. cruzi infection and T. cruzi cell cycle completion. Our present data demonstrate that small inhibitors of the TGF-beta signaling pathway might be potential pharmacological tools for the treatment of Chagas disease.


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