CDK1 and cancer: PPP2R2A is a major heterotrimeric serine/threonine phosphatase, counteracting the actions of Ser/Thr kinases, such as the components of mitogen activated protein kinase (MAPK) and AKT pathways, tumor suppressor pRB and p53, and cyclin-dependent kinase 1 (CDK1) substrates, which are often defective or deregulated in cancer [36].