| Background |
Protein phosphatase 2A (PP2A) is a trimeric protein phosphatase and tumor suppressor that regulates the phosphorylation status of a wide variety of phosphoproteins. PP2A targets include many that play a role in the maintenance and progression of cancer . The cancerous inhibitor of protein phosphatase 2A (CIP2A) is a single pass membrane protein that binds the PP2A catalytic subunit to inhibit PP2A phosphatase activity. CIP2A is normally expressed at low levels in normal cells and tissues, but is elevated in human malignancies where it is thought to be oncogenic. Research studies demonstrate aberrant CIP2A expression in multiple tumor types, including those derived from the head and neck, liver, colon, lung, osteosarcoma, pancreatic, breast, and myeloid cancers. This evidence suggests that CIP2A interacts with many proteins that may play a role in cancer maintenance and progression. Additional studies indicate that CIP2A inhibits PP2A-mediated dephosphorylation of the proto-oncogene Myc at Ser64, which stabilizes and prevents proteolytic degradation of the Myc transcription factor.
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