To test whether FOXO4 is a key mediator of RAS-mutant cancer cell growth arrest and death, we transfected small amounts of the FLAG-tagged wildtype FOXO4 (FLAG-FOXO4WT) or CK1α-resistant mutant of FOXO4 (FLAG-FOXO4S265/268A) in RAS-mutant HCT-116 and SW480 colon cancer cells to test if they are sufficient to arrest cell growth. This evidence concerns the gene CSNK1A1 and cancer.