ST271 is a potent inhibitor of protein tyrosine kinase (PTK), inhibits phospholipase D activation stimulated by fMet-Leu-Phe and PAF, with IC50s of 6.7 and 9 μM, respectively.
ST271 partially inhibits peptide phosphorylation in the membrane preparation and in permeabilized platelets[1]. ST271 (100 μM) causes complete inhibition of formation of inositol phosphates induced by FcγRII cross-linking, but also induces a small (< 30%) but significant inhibition of the response to thrombin and U46619[2].
[1]. Martinson EA, et al. Inhibition of phospholipase D of human platelets by protein tyrosine kinase inhibitors. Cell Mol Biol (Noisy-le-grand). 1994 Jul;40(5):627-34. [2]. Blake RA, et al. Fc gamma receptor II stimulated formation of inositol phosphates in human platelets is blocked by tyrosine kinase inhibitors and associated with tyrosine phosphorylation of the receptor. [3]. Uings IJ, et al. Tyrosine phosphorylation is involved in receptor coupling to phospholipase D but not phospholipase C in the human neutrophil. Biochem J. 1992 Feb 1;281 (Pt 3):597-600.