SMAD4 and gastric cancer: Positive expression rate of TGF-β1 signaling molecules in i-GC and d-GC, respectively, was as follows; TGF-β1 (61 and 34 %), TβR2 (100 and 66 %), Smad4 (26 and 27 %), p-ERK1/2 (82 and 37 %), p-Akt (72 and 69 %), and TAK1 (87 and 83 %) (Fig. 1; Expression data is summarized in Table 4).