EGFR and intervertebral disk degenerative disorder: Previous studies revealed that ErbB signaling regulates cell proliferation, migration, differentiation, apoptosis, and motility by mediating the phosphoinositide 3-kinase/Akt, Janus kinase/signal transducer and activator of transcription, and mitogen-activated protein kinase signaling pathways, with activation of the latter pathway in IDD possibly leading to apoptosis of annulus fibrosus and NP cells (34, 35).