Fig. 1.

SB-505124 and (5Z)-7-Oxozeaenol inhibit both transforming growth factor β1 (TGFβ1)-induced Smad1/5 and Smad2/3 phosphorylation whereas LDN-193189 does not. a Primary bovine chondrocytes were pre-incubated with either 5 μM SB-505124, 0.5 μM (5Z)-7-Oxozeaenol or 0.05 μM LDN-193189 for 1 h, and subsequently stimulated with 1 ng/ml TGFβ1 for 1 h, after which phosphorylated Smads were visualized using western blot by specific antibodies. kDa, kilodalton. b Quantification of the pSmad1/5 signal (as shown in a) in four experiments. pSmad1/5 levels were normalized to vinculin levels and plotted as a relative amount in arbitrary units (AU) compared to the control group: #p ≤ 0.001 compared to unstimulated; ***p ≤ 0.001. c Quantification of the pSmad2 signal (as shown in a) in four experiments. pSmad2 levels were normalized to vinculin levels and plotted as a relative amount in AU compared to the control group: ^# p ≤ 0.001 compared to unstimulated; ***p ≤ 0.001. d Dose-response effect of SB-505124 on TGFβ1 signaling in primary chondrocytes. e Quantification of pSmad levels (shown in d); levels were normalized to vinculin levels and plotted as a relative amount in percentage compared to the control group