Intratissular expression of visfatin/Nampt from osteoarthritic human joint tissues. Human osteoarthritic joint tissues were obtained after surgery, separated, frozen and ground to obtain protein extracts. Western blot analysis of the visfatin/nicotinamide phosphoribosyltransferase (Nampt) protein level in tissues. Left panel: denaturing conditions, showing a monomeric conformation. Right panel: nondenaturing conditions, showing polymeric conformation. Arrows show bands specific to visfatin/Nampt.