The expression pattern for Il1b, a key cytokine implicated in disc degeneration, was similar to that of Mmp13 with no significant age‐by‐tissue compartment interaction, but significant differences between tissue compartment (F1,31 = 46.15, P < .01, partial eta‐square = 0.62) and over time (F3,31 = 3.11, P < .04, partial eta square = 0.25) (Figure 6D). Here, MMP13 is linked to intervertebral disk degenerative disorder.