MV1 is an antagonist of IAP (inhibitor of apoptosis protein), leads to protein knockdown of HaloTag-fused proteins when combined with HaloTag ligand[1].
[1]. Tomoshige S, et al. Efficient protein knockdown of HaloTag-fused proteins using hybrid molecules consisting of IAP antagonist and HaloTag ligand. Bioorg Med Chem. 2016 Jul 15;24(14):3144-8.