MAPK3 and cavernous hemangioma: To further prove that Ccm3−/− cells can form cavernomas and recruit surrounding Ccm3+/+ cells, we isolated endothelial cells from acute P7 Cdh5(PAC)-Cre-ERT2/Ccm3f/f/R26R-Confetti mice and we injected these cells into the brains of adult wild-type mice.