Y-27632 #13624

Y-27632 is a potent and selective ATP-competitive inhibitor of Rho-associated kinases (ROCK), with K_i values of 0.22 µM and 0.30 µM for ROCK1 and ROCK2, respectively. In vitro kinase assays demonstrate that Y-27632 exhibits a 20-fold greater preference for ROCK when compared to citron kinase and protein kinase N (1). Research studies show that Y-27632 treatment of cells leads to inhibition of ROCK phosphorylation of myosin phosphatase subunit 1 (MYPT1) at both Thr853 and Thr696, with a much greater inhibition of Thr853 phosphorylation (2,3). Y-27632 selectively inhibits smooth-muscle contraction by inhibiting Ca²⁺ sensitization (4). Additional research indicates that Y-27632 inhibits dissociation-induced apoptosis of cultured human embryonic stem cells over numerous passages and increases cloning efficiency (5).