Effect of AST intervention on FLS proliferation, cell cycle progression and cell ultrastructure. (A) Inhibition rate in the groups treated with various concentrations of AST under different reaction times. #P<0.05 and ##P<0.01, compared with the 72-h intervention; *P<0.05 and **P<0.01, compared with the 48-h intervention. (B) IC50 value calculated by MTT assay. (C) Cell cycle phase was detected by flow cytometry. (a) Control group; (b) model group; (c) AST group. (D) Quantification of the cell cycle results. ##P<0.01, compared with the control group; **P<0.01, compared with the model group. (E) Control group (magnification, ×12,000). (F) Model group (magnification, ×12,000). (G) AST group (magnification, ×12,000). a, nucleus; b, nuclear membrane; c, mitochondria; d, endoplasmic reticulum; ALS, astragaloside; FLS, fibroblast-like synoviocyte.