STAT3 and cancer: Gene silencing of HIF-1α, the oxygen-sensitive subunit of the heterodimeric transcription factor HIF-1 (HIF-1α/HIF-1β) (Samanta and Semenza, 2017), suppresses the phosphorylation of STAT3 in fibroblasts (Gao et al., 2015), while ouabain reduces HIF-1α levels in cancer and smooth muscle cells (Zhang et al., 2008; Koltsova et al., 2014).