SR-3677 is an effective and specific inhibitor of ROCK2 (IC50: 3 nM).

ROCK1:56 nM, ROCK2:3 nM

SR-3677 has an IC50 of ~3 nM in enzyme and cell-based assays and has an off-target hit rate of 1.4% against 353 kinases, and inhibits only 3 out of 70 non-kinase enzymes and receptors. The IC50 value of SR-3677 for ROCK-I is 56 nM.

SR-3677 increases ex vivo aqueous humor outflow in porcine eyes and inhibiting myosin light chain phosphorylation. Continuous exposure of 25 μM SR-3677 increases the outflow facility by 60% at 1 h perfusion, increasing to 70–80% for the 2–5 h time points.

5 μL mixture of a 1 μM STK2 substrate and ATP (ROCK-I: 4 μM; ROCK-II: 20 μM) in STK-buffer is added to the wells. 20 nL of test compounds (SR-3677) is dispensed. The reaction is started by addition of 5 μL of 2.5 nM. ROCK-I or 0.5 nM ROCK-II in STK-buffer. After 4 h at RT, the reaction is stopped by the addition of 10 μL of 1x antibody and 62.5 nM Sa-XL in the detection buffer.