SMAD2 and gastric cancer: Functionally, we showed that SMAD2 overexpression enhanced cell proliferation, migration and invasion and that inhibition of miR-4256 partly abolished the promoting effect of SMAD2 on GC; in addition, SMAD2 knockdown attenuated malignant biological behavior, and miR-4256 overexpression markedly reversed the inhibitory effect of silencing SMAD2 on GC cell proliferation, migration, and invasion.