The KEGG results indicated that the DEMs between the NSCLC and SCLC groups were clearly related to pathways associated with cAMP signalling, endocrine resistance, leukocyte transendothelial migration, Rap1 signalling and ErbB signalling (p = 1.96 E-04, p = 5.52E-04, p = 0.0027, p = 0.0051, p = 0.0237), as shown in Fig. 5d. Here, EGFR is linked to non-small cell lung carcinoma.