Fig. 7

Contribution of ALK receptors to TGF-β-induced SMAD activation in chondrogenic MSC cultures MSCs were subjected to chondrogenic induction in absence or presence of 10 ng/mL TGF-β1, 500 nM LDN21 to inhibit ALK1/2/3 or 10 µM SB-431542 (SB43) to inhibit ALK4/5, or DMSO as solvent control for 30 min as indicated. (Phosphorylated) SMAD proteins were detected via Western blotting with β-actin detection as internal reference. (A) SMAD1/5/9 detection, (B) SMAD2/3 detection. One representative blot of three experiments with three independent MSC donor populations is shown. The image was cropped for conciseness as indicated and full-length blots are presented in supplementary Fig. S7