Figure 4

FSTL1 enhances proliferation of FLS in a p53- and p21-dependent way. (A) About 2,000 OA FLS cells per well were seeded into a 96-well plate in triplicate (the seeding day was referred to as Day 0, that is, D0). On the subsequent 6 days (referred as to D1 to D6), 5 μg/ml FSTL1 was daily applied to the medium. MTS test was performed daily on D2 to D7. (B) Cells were collected after D4 exposure to 5 μg/ml FSTL1 and western blots for p53 and p21 were conducted. Left panel, representative blots; Right panel, quantification data. Results in (A) and (B) are presented as mean ± (standard deviation) SD of three independent experiments (each FLS cell line from an individual patient was used for each experiment). ^* P <0.05, ^** P <0.01, compared to the vehicle-treated control, Student t test. FLS, fibroblast-like synoviocyte; FSTL1, follistatin-like protein 1; MTS, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; OA, osteoarthritis.