KRIT1, CCM2 and CCM3 deficient endothelial cells and human CCM lesion samples display activated RhoA and increased activity of downstream effectors ROCK1 and ROCK2, which consequently phosphorylate myosin light chain (MLC) and MLC phosphatase, leading to inhibition of the latter [62,73,107–109]. The gene discussed is KRIT1; the disease is cerebral cavernous malformation.