COL2A1 expression in SW1353 (a human chondrosarcoma cell line), Hs819.T (a human chondrosarcoma cell line), and 293T cells was much lower than that in human ACs, while Col2a1 expression in ATDC5 cells (a mouse chondrogenic cell line) was similar to that found in mouse primary ACs (Supplementary Fig. 2a−d). This evidence concerns the gene COL2A1 and chondrosarcoma.