Protein phosphatase 1 regulatory subunit 15A also known as growth arrest and DNA damage-inducible protein GADD34 is a protein that in humans is encoded by the PPP1R15A gene. The Gadd34/MyD116 gene was originally discovered as a member in a set of gadd and MyD mammalian genes encoding acidic proteins that synergistically suppress cell growth. Later on it has been characterized as a gene playing a role in ER stress-induced cell death, being a target of ATF4 that plays a role in ER-mediated cell death via promoting protein dephosphorylation of eIF2α and reversing translational inhibition. This gene is a member of a group of genes whose transcript levels are increased following stressful growth arrest conditions and treatment with DNA-damaging agents. The induction of this gene by ionizing radiation occurs in certain cell lines regardless of p53 status, and its protein response is correlated with apoptosis following ionizing radiation.