SMAD3 and pulmonary arterial hypertension: We found that media, conditioned by PAH PAVSMC (PAH CM), induced significant C-terminal phosphorylation of Smad2 and Smad3 in non-diseased cells, seen in Figure 7A,B, confirming that PAH PAVSMC secrete increased amounts of active TGF-β1 and/or Activin A, shown in Figure 1.