HIF1A and hemangioma: In mice, removal of VHL’s inhibition of HIF via mosaic VHL knockout led to the formation of vascular lesions ranging from hemangiomas to a single mouse that developed an angiosarcoma.110 HIF-1a and HIF-2a expression is reported in a subset of angiosarcomas,111, 112 but HIF-1a does not appear to be a notable driver of angiosarcoma growth.112