ALDH1 has 3 isoforms (ALDH1A1, ALDH1A2 and ALD1A3) and is a marker of both stem cells and CSCs, with expression observed in colon, pancreas, breast and prostate cancers (Brungs et al., 2016; Tomita et al., 2016). This evidence concerns the gene ALDH1A1 and prostate cancer.