SNAI1 and breast cancer: Activated HIF1α or HIF2α directly or indirectly regulate SNAI1, TWIST1 and ZEB1 expression which fosters stemness and metastasis formation in bladder, ovarian, gastric and breast cancer (Yang et al, 2008; Cooke et al, 2012; Liu et al, 2017; Hapke & Haake, 2020; Zhang et al, 2020).