SMAD4 and gastric cancer: Deregulation of this miRNA is important for GC progression because it promotes cell proliferation by down-regulating the expression of CDKN1B (p27kip1) tumor suppressor (Sun et al., 2012) and invasion and epithelial to mesenchymal transition of cancer stem cells by down-regulating the expression of SMAD4 in GC (Pan et al., 2017).