C1QBP and intervertebral disk degenerative disorder: To determine whether C1QBP expression was correlated with IDD, human NP tissues were harvested and divided into two groups according to the Pfirrmann grading system: the mild degeneration group (II-III grade) and the severe degeneration group (IV-V grade), the expression level of C1QBP was measured by RT-qPCR.