The CIP2A protein was originally identified as p90, a cytoplasmic auto-antigen from the serum of a cancer patient. It was later found to inhibit protein phosphatase 2A (PP2A) activity as well as interact with c-myc. CIP2A's inhibitory activity blocks c-myc phosphorylation and its subsequent proteolytic degradation, producing a stable c-myc that promotes aberrant cell growth and transformation. In addition to its role in c-Myc stabilization, CIP2A promotes anchorage-independent cell growth and in vivo tumor formation.
