KRIT1 and cerebral cavernous malformation: Inducible endothelial-specific heterozygous loss of MEKK3, KLF2 and KLF4 in a KRIT1 knockout background reduces CCM lesions, reverses the increase in Rho activation and normalizes MLC phosphorylation, suggesting that changes in RhoA–ROCK activity are downstream of changes in MEKK3 activity [71].