Besides, the JNK/ERK–MAPK and NF-κB signaling pathways in NPCs during IDD, modulated by TNF-α binding to TNF receptors, up-regulate pro-apoptotic and down-regulate anti-apoptotic proteins, thereby inducing apoptosis (Zhang et al., 2019). The gene discussed is MAPK8; the disease is intervertebral disk degenerative disorder.