YBX1, also known as Y box binding protein 1, associates with the selenocysteine insertion sequence and functions in mammalian selenoprotein translation. This protein is a potential drug target in cancer therapy. It helps the replication of adenovirus type 5, a commonly used vector in gene therapy. Thus, YBX1 can cause an "oncolytic" effect in YBX1 positive cancer cells treated with adenoviruses. Recombinant human YBX1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.