Life support:: the α4 phosphatase subunit in cell survival and apoptosis

Reversible protein phosphorylation represents a cellular response to normal physiological processes as well as to cellular insults and stress. Recently, the protein phosphatase-associated alpha A subunit was shown to be required for sustaining cell survival. Lack of alpha 4 leads to apoptotic death of multiple cell types and to the death of the organism. Here, we explore how the phosphatase network might operate in controlling life-and-death decisions. We discuss the relevance of the findings for understanding the action of alpha 4 in cell survival and for better discriminating between a role in maintaining cellular homeostasis, and thus survival, or actively keeping apoptotic cell death in check by targeting effectors of the cell death machinery.