Among the abemaciclib-sensitive CRC cell lines, all four cell lines lacked mutations in CCND1, RB1, and KRAS. The CDKN2A gene was wild-type in HT-29, Caco-2, and SNU-C4 cells, but not in SNU-C5 cells, which harbor a CDKN2A-silencing mutation. This evidence concerns the gene RB1 and colorectal carcinoma.