In colorectal cancer, phosphorylated CTD interacting factor 1 (PCIF1) modulates colorectal cancer growth and response to anti-programmed cell death 1 (PD-1) in a context-dependent mechanism in which PCIF1 directly targets FOS, IFITM3, and STAT1 via N6,2′-O-dimethyladenosine (m6Am) modifications. Here, PCIF1 is linked to colorectal cancer.