TNFRSF9, also known as tumor necrosis factor receptor superfamily member 9, is a member of the TNF-receptor superfamily. This receptor contributes to the clonal expansion, survival, and development of T cells. It can also induce proliferation in peripheral monocytes, enhance T cell apoptosis induced by TCR/CD3 triggered activation, and regulate CD28 co-stimulation to promote Th1 cell responses. The expression of this receptor is induced by lymphocyte activation. TRAF adaptor proteins have been shown to bind to this receptor and transduce the signals leading to activation of NF-kappaB. Recombinant human TNFRSF9, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.