Protein phosphatase 2A (PP2A) is a heterotrimer affecting approximately 60% of all serine/threonine phosphorylations. PP2A functions as a tumor suppressor when it is a trimer (PP2A-A-PP2Ac-B56) containing the B56 subunit. The B56 subunit is known to interact with up to 100 different proteins, but exactly how the PP2Aa/c-B56 complex is disrupted to initiate cancer has been poorly understood until now.