HIF1A and cancer: Neural progenitor cells display increased proliferation in 10% O2 in an effect mediated by HIF-1α, and the moderate induction of HIF-1α in 5% O2 has been shown to promote proliferation of both cancer and non-cancer cell lines, suggesting an important role in normal cell physiology (Carrera et al., 2014; Zhao et al., 2008).