For example, most studies paid their attention on the activation of ER stress or UPR pathway in IVDs via the expression of some ER stress or UPR markers, such as GRP78, CHOP or caspase 12, few studies showed the accumulation of misfolded protein in IVD cells in the process of IDD. The gene discussed is HSPA5; the disease is intervertebral disk degenerative disorder.