CRYAB is expressed in the basal cells of normal ductal epithelium, but its expression is robustly elevated in breast cancer as detected by immunohistochemistry (IHC) methods (Kabbage et al. 2012; Moyano et al. 2006) and in the rare, but aggressive, metaplastic subtype of triple negative breast carcinomas (TNBC; ER−/PR− HER2−; (Sitterding et al. 2008)) that metastasize (Koletsa et al. 2014; Malin et al. 2016; Voduc et al. 2015). This evidence concerns the gene PGR and breast cancer.