GADD45GIP1, also known as CRIF1, is a nuclear protein that plays a role in apoptosis control. This protein is expressed in a variety of tissues, including heart, thyroid, trachea, kidney, ovary, pancreas, testis and stomach. It functions as a negative regulator of G1 to S phase cell cycle production, specifically by working with GADD45 proteins to inhibit the activity of cyclin-dependent kinases. Recombinant human GADD45GIP1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.