RETN and cancer: Resistin is a 12.5 kDa protein that enhances the proliferation of mesenchymal, smooth muscle, and granulosa cells.26-29 CD40 plays a role in microglia, B cell, and cancer cell proliferation.13-15 CD40 is a 48kDa transmembrane protein that can undergo enzymatic cleavage (proteolysis) of its extracellular domain which releases a soluble extracellular component of the protein (sCD40) that is 18 kDa in size.16