RSL1D1 (ribosomal L1 domain containing 1) is an RNA-binding protein that functions as a master regulator of cellular proliferation and senescence in cancer. Structurally, RSL1D1 comprises a ribosomal L1 domain and a lysine-rich region, both essential for its biological function 1. Primary mechanistically, RSL1D1 inhibits PTEN translation by binding to its mRNA 3'-UTR, thereby promoting cell proliferation and delaying senescence 1. In colorectal cancer (CRC), RSL1D1 additionally suppresses autophagy through interaction with RAN, inhibiting its deacetylation and preventing STAT3-regulated autophagic programs 2. RSL1D1 also promotes p53 degradation by recruiting wild-type p53 to HDM2, though mutant p53 variants escape this regulation 3. RSL1D1 regulates iron homeostasis by stabilizing FTH1 mRNA; its knockdown causes ferroptosis through ferrous iron accumulation 4. Clinically, elevated RSL1D1 correlates with poor CRC prognosis and is upregulated across multiple cancer types 5. Beyond cancer, RSL1D1 is essential for embryonic development; its oocyte-specific knockout causes preimplantation embryo arrest through defective zygotic genome activation 6. These findings establish RSL1D1 as a pan-cancer oncogenic regulator and potential therapeutic target.