Rapamycin restores the proliferation and chondrogenic differentiation capacity and attenuates senescence of IL-1β-treated SFZCs. SFZCs were treated with IL-1β (20 ng/ml) and (or) RA (100 nM) for 5 days. (A) Immunofluorescent staining of LC3 and quantitative analysis of LC3 puncta. (B) SA-β-gal staining and quantitative analysis of SA-β-gal-positive cells. (C) Western blot analysis of senescence marker p53. (D and E) mRNA Expression levels of SASP factors Mmp-3 and Mmp-13 were determined using RT-qPCR. (F) Cell proliferation capacity was evaluated using a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay. (G) RT-qPCR analysis of four chondrogenic differentiation markers: Sox9, Prg4, Aggrecan, and Col II. IL-1β = interleukin-1β; SFZCs = superficial zone cells in articular cartilage; LC3 = light-chain 1 protein 3; SA-β-gal = senescence-associated β-galactosidase; mRNA = messenger RNA; SASP = senescence-associated secretory phenotype; RT-qPCR = reverse transcription-quantitative PCR; RA = rapamycin. *P < 0.05, **P < 0.01, and ***P < 0.001.