Wang et al. discovered that miR-21 is upregulated in IDD tissues and positively correlated with the degradation grade, which indicates miR-21 cannot only inhibit NP cell apoptosis and promote proliferation as mentioned above, but also promote ECM degradation through repressing the PTEN/AKT/mTOR signaling pathway [38]. The gene discussed is PTEN; the disease is intervertebral disk degenerative disorder.