IL1B and Arthritis: Wehling and co-workers recently reported that IL-1β and TNF-α inhibited chondrogenesis from mesenchymal stem cells into chondrocytes in a dose-dependent manner and this was associated with a marked activation of NF-κB [39], also Polzer and co-workers reported that although wild-type mice showed no signs of cartilage damage, human TNF transgenic mice exhibited progressive proteoglycan loss starting at the clinical onset of arthritis [40].