Epidermal growth factor (EGF) and tumor necrosis factor alpha (TNF-α) differentially regulate the activity of the type II collagen enhancer. Chondrocytes were co-transfected with the type II collagen enhancer luciferase reporter and the pSV40-RL constructs. The transfected cells were treated with vehicle (CNTL), TNF-α (30 ng/ml), EGF (10 ng/ml) or TNF-α + EGF, and the reporter activities were analyzed after 24 hours. Values of relative luciferase expression (corrected for transfection efficiency) were compared using one-way analysis of variance followed by a Tukey–Kramer post-test, and are presented as the mean ± standard error of the mean. a Significantly different from others at P < 0.001. Data are representative of three independent experiments. RLU, relative luciferase units.