Immunostaining of lubricin of femoral articular cartilage at contact, transitional, and non-contact areas in the control (CON), low- (LIR), moderate- (MIR), and high-intensity (HIR) groups. Lubricin was mainly immunolocalised to chondrocytes and extracellular matrix (ECM) in the superficial zone of normal cartilage. Markedly increased staining of lubricin was found in the LIR and MIR groups, whereas little staining was detected in the HIR group. NCA: non-contact area, TA: transitional area; CA: contact area. Scale bar = 50 μm.