SMAD2 and myelodysplastic syndrome: Recombinant GDF-11 at a concentration of 0.1 μg/ml was found to induce Smad2/3 signaling in both healthy and MDS MSCs, while a concentration of 10 μg/ml RAP-536 was sufficient for 50% inhibition of Smad2/3 phosphorylation in GDF-11-treated cells.