GADD45A, also named as DDIT1 and GADD45, belongs to the GADD45 family. It binds to proliferating cell nuclear antigen.GADD45A may 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.GADD45A plays an essential role in active DNA demethylation during terminal osteogenic differentiation of adipose-derived mesenchymal stem cells.