HIF1A and cancer: Leptin signaling promotes tube formation through interaction with the VEGFR2 downstream signaling cascade in cultured human umbilical vein ECs (HUVECs) (Garonna et al. 2011), whereas in cancer cells, LEPR activation stimulates VEGF-A expression mainly through hypoxia-inducible factor-1 α (HIF-1α) and nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) (Gonzalez-Perez et al. 2010).