Recent studies comparing gastric cancer and normal tissue have identified a number of genetic markers, including diagnostic markers [NF2[7], INHBA[8], SFRP4[9]], prognostic markers [CD9[10], CDH17[11], PDCD6[12]], and gastric cancer-associated genes [MUC13[9], CLDN1[13], Ki67 and CD34[14]]. The gene discussed is CD9; the disease is gastric cancer.