SMAD7 and gastric cancer: Furthermore, 14 of the identified genes (AGT, APOC1, APOE, AXIN2, CEACAM5, ERBB2, HSPA13, ID1, KLK12, MMP9, PPP1R1B, PTPRA, SERPINB5, and SMAD7) have previously been associated with malignant gastric tumors.