IHC analysis of three distinct CCM specimens from KRIT1 loss-of-function mutation carriers with confirmed diagnosis of CCM revealed increased levels of PSSG adducts in endothelial cells lining the lumen of abnormally dilated CCM vessels (Figure 8A,B) as compared with perilesional normal vessels (Figure 8C,D), demonstrating that the enhanced protein S-glutathionylation caused by KRIT1 loss-of-function occurs also in vivo, suggesting a potential relationship with CCM disease. Here, KRIT1 is linked to cerebral cavernous malformation.