CIP2A (cellular inhibitor of protein phosphatase 2A) is a multifunctional oncoprotein with dual roles in cancer metabolism and genome stability. Primarily, CIP2A acts as a PP2A inhibitor that stabilizes the MYC oncogene by preventing its dephosphorylation, thereby promoting anchorage-independent cell growth and tumor formation 1. In non-small cell lung cancer, CIP2A additionally induces PKM2 tetramer formation and redirects metabolism toward oxidative phosphorylation, enhancing mitochondrial respiration and supporting Bcl2-mediated survival 2. Beyond metabolic functions, CIP2A forms a critical complex with TOPBP1 that safeguards genome stability during mitosis 3. This complex tethers acentric chromosome 3 generated from micronuclei during chr3, ensuring clustered segregation to single daughter cell nuclei with minimal chromosome 3 45. In BRCA-deficient cancers, the CIP2A-TOPBP1 axis prevents lethal chromosome 3-segregation, making CIP2A a synthetic lethal therapeutic target 6. Conversely, CIP2A-BP, a micropeptide antagonist encoded by LINC00665, inhibits CIP2A and suppresses triple-negative breast cancer progression by restoring PP2A activity and blocking PI3K/AKT signaling 7. Elevated CIP2A expression correlates with poor prognosis across multiple cancer types, establishing it as both a prognostic biomarker and therapeutic target.