POU5F1 and cancer: Accordingly, HIF-2α (not HIF-1α) can favor proliferation of cancer cells by promoting c-Myc activity, and radio- and chemo-resistance, self-renewal capability, and stem cell phenotype in non-stem cell populations via Oct-4, Nanog, and c-Myc as well as by contributing to the maintenance of cancer stem cell (CSCs) properties [19,20].