ATF4 and intervertebral disk degenerative disorder: In addition, previous studies showed that silencing some molecules in the downstream of UPR, such as ATF4 and CHOP, successfully reduced the expression of IL-6 and prevented the process of IDD, indicating that manipulating some molecules in UPR pathway could be a potential molecular target for IDD prevention (Fujii et al., 2018; Krupkova et al., 2018).