In the brain capillary-venous system, where CCM lesions develop, the ECs express the lowest levels of KLF2/4 in the human body (Gene expression for KLF2 ENSG00000127528.5, KLF4 ENSG00000136826.10, GTEx Analysis Release V7, dbGaP Accession phs000424.v7.p2). This evidence concerns the gene KLF4 and cerebral cavernous malformation.