KIF20A and intervertebral disk degenerative disorder: This process brought abnormal gene expression of PLK1, CDC20, KIF20A, UBE2C, RRM2, and CCNB1 and pathway of cell cycle, and amplification of multiple down-stream cascades from pro-inflammatory M1 macrophages, together with the cytokines they secrete, aggravate IDD pathology, hinder recovery, and cause pain, while anti-inflammatory and remodeling M2 macrophages show an increasing expression of growth factors and anti-inflammatory agents (Figure 9).