KRIT1 and infection: To study the cellular functions of CCM1, researchers have established isogenic mouse embryonic fibroblasts (MEFs) from wild-type (WT) and Ccm1-knockout (KO) mice and created Ccm1-knockin (KI) fibroblasts by stable infection of Ccm1-KO fibroblasts with a lentiviral vector encoding human KRIT1 [4,5,6,7,8].