WNK2 and intervertebral disk degenerative disorder: Further studies are needed also to investigate possible relationships of these molecules with perturbations of Wnt/β-catenin, Notch, interferon-alpha, hypoxia, nuclear factor kappa B (NF-kB), Sirtuin 3 and mitogen-activated protein kinase (MAPK) pathways that have been identified as important regulators of progress of disc degeneration [7,44,45,46,47,48,49].