Considering the positive results of blockade of the co-inhibitory signal induced by the binding of CTLA-4 with CD80 for patients with melanoma, it is believed that it is important to obtain a greater understanding of expression data and the function of CD80 in gastric cancer, as well as to characterize the existing molecular interaction between the CTLA-4 and CD80 proteins. Here, CTLA4 is linked to gastric cancer.