To evaluate the accuracy of the predictive signatures for the chemotherapeutic response, we designed PRM strategy to quantify these signature proteins in FFPE tumor tissues from the new independent cohort composed of 60 GC patients receiving either DOS (N = 20: DSG, N = 10; DNSG, N = 10), XELOX (N = 20: XSG, N = 10; XNSG, N = 10), or anti-HER2 (N = 20: HSG, N = 10; HNSG, N = 10) therapies (Supplementary Data 11). This evidence concerns the gene ERBB2 and gastric cancer.