KRIT1 is a 75 kDa scaffolding protein that functions as a critical regulator of vascular integrity and endothelial cell homeostasis 1. As a component of the CCM signaling pathway, KRIT1 maintains endothelial barrier function by limiting inflammatory responses and promoting a quiescent endothelial phenotype 1. Mechanistically, KRIT1 inhibits endothelial proliferation and migration while suppressing pathological angiogenesis through activation of the NOTCH-dependent KLF2/KLF4 signaling cascade 2. KRIT1 establishes proper endothelial cell polarity and vascular lumen formation by recruiting the Par polarity complex and regulating integrin signaling 1. Additionally, KRIT1 maintains intracellular reactive oxygen species homeostasis through FOXO1 and SOD2-mediated antioxidant pathways, preventing oxidative damage and facilitating cell cycle arrest 3. Loss-of-function mutations in KRIT1 cause cerebral cavernous malformations (CCM1), characterized by abnormal vessel formation, barrier dysfunction, increased endothelial proliferation, and altered gene expression 4. KRIT1 is widely expressed beyond endothelial tissue, suggesting roles in non-vascular contexts 1. These multifaceted functions make KRIT1 essential for maintaining vascular homeostasis and preventing pathological vascular remodeling.