The KEGG enrichment analysis again enriched the indicated differentially expressed immune-related genes in multiple immune-related pathways, including “T cell receptor signalling pathway”, “B cell receptor signalling pathway”, “Th1 and Th2 cell differentiation”, “Th17 cell differentiation”, “Natural killer cell-mediated cytotoxicity”, “EGFR tyrosine kinase inhibitor resistance”, “Intestinal immune network for IgA production”, and “PD-L1 expression and PD-1 checkpoint pathway in cancer” (Additional file 2: Fig. S1B). Here, EGFR is linked to cancer.