Tomatidine inhibits IL-1β-induced MAPK activation in primary chondrocytes. (A) Representative western blot images and (B) Histogram plot shows the levels of phospho-P38, P38, phospho-ERK, ERK, phospho-JNK, and JNK proteins relative to GAPDH (internal control) levels in the primary chondrocytes treated for 30 mins with 2.5, 5, or 10μM tomatidine alone or in combination with 10ng/mlIL-1β. DMSO was used as control. The values are means ± SD of triplicate experiments. #p < 0.05 compared with the control group. *p < 0.05 and **p < 0.01 compared with the IL-1β group.