ROCK-IN-2 is a highly potent inhibitor of human ROCK-1 and ROCK-2, with IC50s of 0.6 and 1.1 nM, respectively, and also inhibits murine ROCK-2 or rat ROCK-2 with IC50s of 2.4 and 0.8 nM, respectively. ROCK-IN-2 also inhibits receptor tyrosine kinases TRK and FLT3, with IC50s of 252 and 303 nM, respectively, but shows slight inhibition of MLCK and ZIP-kinase with IC50s of 7.4 μM and 4.1 μM, respectively. ROCK-IN-2 induces vasorelaxation in vitro, and suppresses the phenylephrine-induced contraction of rabbit saphenous artery in a concentration dependent manner with an IC50 value of 65 nM.