Correlation analysis between RFC4 and checkpoint gene expression in different types of cancers showed a high correlation with immune genes including CCL4, CCL16, HLA family genes, TNFRSF8, TNFRSF14, TNFRSF18, CD70, CD44 (p < 0.05, Figure S8), CD276, CX3CL1 and VGEGFA (p < 0.05, Figure S9). The gene discussed is TNFRSF18; the disease is cancer.