Cell viability is maintained in the presence of tumor necrosis factor alpha (TNF-α) and/or epidermal growth factor (EGF). Subconfluent monolayers of chondrocytes were treated with vehicle, TNF-α (30 ng/ml), EGF (10 ng/ml) or TNF-α + EGF for 24 hours. Cell viability was assessed by MTT assay. Data shown are combined from four independent experiments, presented as the mean corrected absorbance ± standard error of the mean analyzed by repeated-measures analysis of variance. a Significant difference from control (P < 0.01, n = 4). OD, optical density.