MAPK3 and cerebral cavernous malformation: To study whether the CCM lesions have a clonal origin, the Cdh5(PAC)-Cre-ERT2/R26R-Confetti mice were crossed with Ccm3f/f mice (Cdh5(PAC)-Cre-ERT2/Ccm3f/f/R26R-Confetti), which develop CCM lesions upon tamoxifen injection that resemble the human pathology24.