Selective inhibitor of the Rho-associated protein kinase p160ROCK. Ki values are 0.14, 26, 25 and > 250 μM for p160ROCK, PKC, cAMP-dependent protein kinase and myosin light-chain kinase respectively. Also inhibits the protein kinase C-related protein kinase, PRK2 (IC50 = 600nM). Smooth muscle relaxant and orally active in vivo. Increases survival rate of human embryonic stem (hES) cells undergoing cryopreservation.