In T-cells, functions as a regulator of p38 MAPKs by inhibiting p88 phosphorylation and activity (By similarity). Might affect PCNA interaction with some CDK (cell division protein kinase) complexes; stimulates DNA excision repair in vitro and inhibits entry of cells into S phase. Interacts with MAPK14 (By similarity). Predominantly monomeric but also forms dimers and other oligomers as concentration increases. Interacts with GADD45GIP1. Interacts weakly with PCNA. Interacts with AURKA, likely to compete with dimerization. By UV irradiation, X-rays, growth arrest and alkylating agents. The induction is mediated by some kinase(s) other than PKC. Belongs to the GADD45 family. GADD45A entry