MiR-24 downregulation is sufficient to trigger p16INK4aexpression and matrix metalloproteinase 1 (MMP1) production in mature chondrocytes. Osteoarthritis (OA) human primary chondrocytes were transfected with irrelevant antagomiR (Ctrl) and antagomiR-24 (A24) at a concentration of 100 nM. They were placed in pellet culture conditions for 7 days. (A, B) Gene expression analysis was performed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) for miR-24 and p16INK4a (n = 4). (C) p16INK4a protein expression by immunohistochemistry (IHC) on pellet paraffin-embedded sections. Images were taken with a ×20 objective. (D-G) MMP1, MMP13, interleukin-6 (IL-6), and IL-8 secretion were measured by enzyme-linked immunosorbent assay (ELISA) (n = 4). Data are shown as mean ± standard deviation (SD). *P <0.05.