Creg1, also known as Cellular repressor of E1A-stimulated genes1, was antagonizes transcriptional activation and cellular transformation by E1A. This protein both activates and represses gene expression to promote cellular proliferation and inhibit differentiation. Creg1 increases EC filopodia formation and vascular assembly via ILK-Cdc42 activation and promotes neovascularization, which might be a therapeutic target for ischemic injury. Recombinant mouse Creg1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.