SMAD2 and myelodysplastic syndrome: First of all, it was shown that MDS patients showed a higher number of bone marrow cells with activated phosphorylated SMAD2 (p-SMAD2) and a greater intensity of p-SMAD staining, compared to normal controls, and that therefore SMAD2 is constitutively activated and overexpressed in the hematopoietic cells of MDS patients.