The level of phosphorylated Smad2 (P-Smad2) and total Smad2 (Smad2) was assessed by immunoblotting and β-actin was used as a loading control. Lower bar graphs show WB quantification of P-Smad2 (P-S2) normalized to β-actin. (A) Activation of the pathway was assessed in non-Group 3 (blue) and Group 3 (yellow) MB cell lines in response to TGFβ or ActivinB stimulation for 1h. 