Human TNF alpha Recombinant Protein. TNF alpha is a multifunctional proinflammatory cytokine that belongs to the tumor necrosis factor (TNF) superfamily. This cytokine is mainly secreted by macrophage and bind to its receptors, TNFRSF1A/TNFR1 and TNFRSF1B/TNFBR. TNF alpha is involved in the regulation of immune cells, cell proliferation, differentiation, apoptosis, lipid metabolism, and coagulation. TNF alpha exists as a multimer of two, three, or five noncovalently linked units, but shows a single 17 kDa band following SDS-PAGE under non-reducing conditions. Knockout studies in mice also suggested the neuroprotective function of TNF alpha, and has been observed to causes tumor necrosis when injected into tumor-bearing mice. Other functions