Cancerous inhibitor of protein phosphatase 2A (CIP2A)

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a regulatory oncoprotein encoded by the *KIAA1524* gene, also known as p90 or cellular inhibitor of PP2A[1][2][5]. It inhibits the tumor-suppressive activity of the protein phosphatase 2A (PP2A) holoenzyme by preventing dephosphorylation of several key substrates, most notably c-Myc, leading to oncogenic stabilization and promoting tumor cell growth, proliferation, and survival[1][3][5]. CIP2A is highly overexpressed in a wide range of human malignancies—including breast, lung, colon, gastric, prostate, and head and neck cancers—where its high expression is correlated with poor prognosis, increased tumor aggressiveness, and resistance to certain therapies (such as imatinib in chronic myeloid leukemia)[1][5][6]. CIP2A’s interaction network, post-translational modifications, and exact structural details are still being investigated, and multiple approaches—including targeting protein interactions (e.g., with 14-3-3 proteins)—are under study for therapeutic exploitation[4]. Serum antibodies to CIP2A may function as early cancer biomarkers, reflecting its clinical relevance and utility[5]. Despite its critical role in human cancer, animal models suggest that pharmacological inhibition of CIP2A may be well tolerated, supporting its candidacy as a drug target[1].

Other names

Cellular inhibitor of protein phosphatase 2AKIAA1524p90 (tumor-associated antigen)CIP2A/p90

Inhibition of PP2A-mediated protein dephosphorylation; Stabilization of oncogenic proteins (e.g., c-Myc); Promotion of malignancy by blocking the tumor suppressor activity of PP2A[1][4][5]