The expression correlation between the identified genes, PD-L1, and PD-L2 in individual LUAD and LUSC tumor samples is illustrated in Additional file 11: Fig. S3A and B. The examination of available LUSC and LUAD PD-L1 protein expression data also revealed expression correlation with PD-L1 protein except for APOL6 mRNA (Additional file 11: Fig. S3A and B). The gene discussed is PDCD1LG2; the disease is neoplasm.