KRIT1 and cavernous hemangioma: The increase in KLF4 was observed also in cultured human brain ECs (hCMEC/D3) when Ccm1 was silenced (Fig 2A) and, most importantly, immunohistochemical analysis of tissue biopsies of CCM1 familial patients confirmed the increase in KLF4 nuclear signal in ECs lining the cavernomas in comparison with normal peri‐lesion vessels (Fig 2B).