SMAD3 and gastric cancer: In a recent study, it was found that when MSCs are cocultured with GC cell lines, TGF-β1 secreted by MSCs can be directly combined with TGFβR-I and TGFβR-II in GC cells to activate SMAD2 and SMAD3 and then induce the upregulation of MACC1-AS1 in GC cells.