The decision to use ALDH1A2 as a seed for our case study comes from the increasing evidence for the role of RAs in mammalian homeostasis and disease, especially the intimate association of the RA signaling pathway with a variety of cancers, including leukemia, neuroblastomas, and carcinomas, as well as gastric, ovarian, lung, breast, colon, rectal, pancreatic, and PCas (18–20). The gene discussed is ALDH1A2; the disease is leukemia.