2-[[1-(3-Chlorophenyl)-4-oxo-5H-pyrazolo[5,4-d]pyrimidin-6-yl]sulfanyl]propanamide

HS 38 is a specific serine/threonine protein kinase inhibitor that affects the regulation of programmed cell-death and phosphorylation of smooth-muscle myelin.

HS38 is a potent and selective ATP-competitive inhibitor of Death-associated protein kinases DAPK1 (IC50 = 200 nM, 89% inhibition at 10 RM) and ZIPK (Zipper-interacting protein kinase, also called DAPK3) th at regulate programmed cell death, and also inhibits the closely related PIM3 kinase (IC50 = 200 nM, 76% inhibition at 10 RM). In addition to mediating apoptosis, DAPK1 and ZIPK regulate both non-muscle and smooth muscle myosin phosphorylation. HS38 specifically targeted ZIPK in smooth muscle, and decreased contractile force generated in mouse aorta, rabbit ileum, and calyculin A stimulated arterial muscle.