Yuan et al. have also previously demonstrated that there is heterogeneity in the proportions of PD-1 positive CD8 T-cells present within the tumor, in the metastatic lymph nodes and in tumor-free lymph nodes from patients with gastric cancer, suggesting that the location of the CD8 T-cells influences functional complexity of this heterogenous cell population. The gene discussed is PDCD1; the disease is neoplasm.