CIP2A and breast cancer: Cancerous inhibitor of protein phosphatase 2A (CIP2A), a well-known oncoprotein that inhibits tumor suppressor protein phosphatase 2A (PP2A), is overexpressed in about 70% of various cancer types, such as non-small cell lung cancer (NSCLC), GC, and breast cancer [21,22,23,24,25,26].