KLF4 and cavernous hemangioma: At P8, almost 100% of the endothelial cells that lined the cavernomas were KLF4-positive (i.e. bona fide endothelial cells undergoing EndMT), which then declined during the increase in the size of the cavernomas to 70% KLF4-positive cells at P14 and 40% KLF4-positive cells at P30 (Fig. 4b).