Although our study showed the importance of ER stress-NFκB-USP9X-Cx43 axis in the development of OPLL, further studies are needed to understand USP9X, Cx43-binding proteins, and other factors that might be involved in or contribute to OPLL progression and the development of novel therapeutic approaches for OPLL. This evidence concerns the gene NFKB1 and ossification of the posterior longitudinal ligament of the spine.