LEP and breast cancer: The associations between HIF-1α and the leptin system identified by us in this study confirm the results obtained by Cascio et al. (2008), Bartella et al. (2008) and Garofalo et al. (2006) who demonstrated that physiologic hypoxia and/or accumulation of HIF-1α due to hypoxia-mimicking conditions or stabilization of HIF-1a by growth factors can stimulate leptin and/or ObR expression in breast cancer cells [34,36,37].