Three major downstream signaling pathways activated by EGFR have been identified: (1) the rat sarcoma (RAS)/rapidly accelerated fibrosarcoma (RAF)/mitogen-activated protein kinase (MAPK) pathway; (2) the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) pathway; and (3) the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) pathway [18,19]. Here, EGFR is linked to fibrosarcoma.