HIF1A and breast cancer: In breast cancer cells, it targets the E3 ubiquitin-protein ligase FBXW7 (F-box and WD repeat domain-containing 7) [61], whereas in prostate cancer cells its targets are two negative regulators of HIF-1 signaling: PHDs (prolyl hydroxylase domain enzymes) and FIH1 (factor inhibiting HIF-1) [62].