Recombinant human Cystatin-9 protein

Cystatin 9, also known as CST9, is a member of the CRES (cystatin-related epididymal spermatogenic) subfamily. The CRES (cystatin-related epididymal spermatogenic) protein defines a newsubgroup in the family 2 cystatins of the cystatin superfamily. Some of the members are active cysteine protease inhibitors, while others have lost or perhaps never acquired this inhibitory activity. CST9 is expressed in heart, placenta, lung, liver, skeletal muscle and pancreas. CST9 is thought to play a role in hematopoietic differentiation or inflammation. It has also been shown to be upregulated by LPS in some cancer cell lines, such as promyelocytic leukemia (HL-60) and myelomonocytic leukemia. Recombinant human CST9 protein, fused to His-tag at N-terminus, was expressed in E. coli.