The key proteins regulated by EGFR, which have been extensively studied in relation to the intracellular mechanisms of NSCLC, involve three major signaling pathways: rat sarcoma virus protein (Ras)/rapidly accelerated fibrosarcoma kinase (Raf)/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK), phosphoinositide 3-kinase (PI3K)/AKT, and signal transducer and activator of transcription 3 (STAT3) [26,27,28]. Here, EGFR is linked to non-small cell lung carcinoma.