Aldehyde dehydrogenase isotype 1A1 (ALDH1A1) is another cancer stem cell marker that has been found to be overexpressed in highly aggressive PCa, suggesting that it might also be of interest to study in this context as a possible target for CuCl2-based therapy (Kalantari et al., 2017b). This evidence concerns the gene ALDH1A1 and cancer.