Stress-induced-phosphoprotein1 (STI1), also known as HOP, belongs to the large group of co-chaperones. The main function of STI1 is to link Hsp70 and Hsp90 together. But recent investigations indicate that it also modulates the chaperone activities of the linked proteins and possibly interacts with other chaperones and proteins. It forms a complex with HSC70 and HSPCA/HSP-86 and HSPCB/HSP-84, as well as interacting with PACRG. Recombinant human STI1, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.