APC and colorectal carcinoma: This quest has led us to focus on CRC cell biology, the role of the adenomatous polyposis coli (APC) gene in colon tumorigenesis, how retinoic acid (RA) and neuroendocrine cell (NEC) signaling controls cellular differentiation, and the mechanisms responsible for the overpopulation of stem cells (SCs) that drives tumor growth (reviewed in [1]).