CIP2A and breast cancer: Breastcancer is the most frequently occurringcancer type in womenworldwide.1 An oncoprotein found overexpressedin almost all cancer types, including breast cancer, is a cancerousinhibitor of protein phosphatase 2A (CIP2A).2 CIP2A overexpression has been correlated with a poor clinical outcomeand a resistance to treatment.3−7 Specifically, in breast cancer, CIP2A overexpression was associatedwith tumor aggressiveness and the promotion of malignant growth.8 CIP2A has primarily been characterized in cancercells as a direct inhibitor of protein phosphatase 2A (PP2A).