Aspirin reversed TNF‐α‐promoted catabolic markers expression during chondrogenesis of BMMSCs. (A, B) Relative mRNA and protein expression levels of catabolic markers (ADAMTS4, MMP9, and MMP13) were measured in BMMSCs treated with or without TNF‐α and aspirin for 7 days by qRT‐PCR and western blot analyses, respectively. (C, D) Relative mRNA and protein expression levels of catabolic markers (ADAMTS4, MMP9, and MMP13) were measured in BMMSCs treated with or without TNF‐α and aspirin for 14 days by qRT‐PCR and western blot analyses, respectively. (E, F) Relative mRNA and protein expression levels of catabolic markers (ADAMTS4, MMP9, and MMP13) were measured in BMMSCs treated with or without TNF‐α and aspirin for 21 days by qRT‐PCR and western blot analyses, respectively. Data in A, C, and E are given as the mean ± SD of three independent experiments. ADAMTS4, ADAM metallopeptidase with thrombospondin type 1 motif 4; GAPDH, glyceraldehyde‐3‐phosphate dehydrogenase; MMP9, matrix metallopeptidase 9; MMP13, matrix metallopeptidase 13. *p < 0.05, **p < 0.01, ***p < 0.001