PP2A: Unveiling a Reluctant Tumor Suppressor

Although evidence has suggested that the serine/threonine protein phosphatase 2A (PP2A) might be a tumor suppressor protein, it has been difficult to pin down its role in tumor suppression because it acts in a wide variety of signaling pathways. Recent findings, including work in this issue by Junttila et al. (2007), provide convincing evidence that suppression of PP2A activity cooperates with other oncogenic changes to cause transformation of multiple cell types.