CD274 and cancer: The KEGG signaling pathway was also enriched in several signaling pathways related to immune cells, e.g., leukocyte transendothelial migration, natural killer cell-mediated cytotoxicity, neutrophil extracellular trap formation, PD-L1 expression and the PD-1 checkpoint pathway in cancer, the T-cell receptor signaling pathway, Th1 and Th2 cell differentiation and Th17 cell differentiation.