(A) Immunoblot analysis of phosphorylated Smad2 (P-Smad2) in Group 3 MB cell lines and PDXs. The level of total Smad2 (Smad2) was assessed and β-actin was used as a loading control. Quantification of P-Smad2 (P-S2) to β-actin are shown on right panel. Right (A) panels represent the relative quantification of P-Smad2 normalized to β-actin. Bars represent the mean ± SD. Number of replicates is n≥3. 