Because overexpression of Smurf2 in cultured fibroblasts induces senescence26 and senescent cell accumulation in discs is important for disc degeneration,27 we examined whether the CLCs overexpressing Smurf2 in Col2a1‐Smurf2 transgenic mouse discs became senescent by examination of senescent markers, SA‐β‐gal, and p53/p21/p16 activation.26 It was rare to detect SA‐β‐gal‐positive cells in 10‐month‐old WT mouse discs; however, in the age‐matched transgenic mice, ∼27% of the disc cells, which were mainly CLCs in the AF, were positive (Fig. 1A). This evidence concerns the gene COL2A1 and intervertebral disk degenerative disorder.