HIF1A and breast carcinoma: Leptin and ANGPTL-4 have previously been reported to be regulated by hypoxia in a HIF-1-dependent manner in adipocytes, human skin fibroblasts, HeLa cells, and MCF-7 breast cancer cells (leptin) [32-34], and in cadiomyocytes (ANGPTL-4) [35], but none of these studies addressed the involvement of the HIF-2 isoform.