Drug discovery in cancer research has thus far been applied to ALDH1a1, ALDH1a3, and ALDH3a1 while drug discovery in substance abuse has focused on ALDH2, and discovery in the male contraceptive space has focused on ALDH1a1/a2 or RARα (Koppaka et al., 2012). Here, ALDH1A1 is linked to cancer.