SPRY domain-containing SOCS box protein 1 (SPSB1), also known as SSB1, is a member of the SOCS box protein subfamily. This protein contains a central SPRY domain and a C-terminal SOCS box. Although some of the SOCS protein subfamilies function as adaptors for a large family of ubiquitin-protein isopeptide ligases to regulate certain signaling pathways, the function of the SSB subfamily remains to be determined. SPSB1 may play an important role in enhancing the HGF-induced Erk-Elk-1-SRE pathway. Over expression of SPSB1 exhibited no effect on the basal level or epidermal growth factor-induced SRE-luciferase activity. Recombinant human SPSB1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.