The results showed that DPP4 expression significantly correlated with infiltration of CD8+ T cells (Figure 5A), CD4+ T cells (Figure 5B), Treg (Figure 5C), B cells (Figure 5D), NK cells (Figure 5E), dendritic cells (Figure 5F), neutrophils (Figure 5G), macrophages (Figure 5H), monocytes (Figure 5I), and cancer-associated fibroblasts (Figure 5J) in pan-cancer patients. This evidence concerns the gene CD4 and cancer.