Fig 2: Comparison of histone marks H3K27me3 and H4K20me1 in OA and N cartilage by Western blotting. Proteins from total extract (T), cytosolic fraction (CF) and histone extract (H) were loaded. Ten micrograms of protein were loaded in each lane. (A) H3K27me3 (#9733, Cell Signaling Technology, 1:1000) expression relative to H3 (#14269, Cell Signaling Technology, 1:10,000) in OA and N cartilage. (B) H4K20me1 (39027, Active Motif, 1:1000) expression relative to H4 (61521, Active Motif, 1:10,000) in OA and N cartilage. Secondary antibody Rabbit IgG HRP Linked Whole Ab (NA934, 1:2000) and Mouse IgG HRP Linked Whole Ab (NA931, 1:2500) were used.

Fig 3: Analysis of different protein concentrations to study H3K27me3 in OA1 cartilage by Western blotting. The weight of the starting material was 1.20 g. (A) SDS-PAGE electrophoresis was performed using 4–20% Mini-PROTEAN® TGXTM Precast Protein Gels (Bio-Rad). (B) SDS-PAGE electrophoresis was performed using a single-percentage polyacrylamide gel (20%). Both gels were transferred to 0.2 µm nitrocellulose membranes (Bio-Rad) to incubate them with primary antibodies against H3K27me3 (#9733, Cell Signaling Technology, 1:1000) overnight at 4 °C and H3 (#14269, Cell Signaling Technology, 1:10,000) for 5 min (A) and 1 h (B) at room temperature (RT). Secondary antibodies Rabbit IgG HRP Linked Whole Ab (NA934, 1:2000) and Mouse IgG HRP Linked Whole Ab (NA931, 1:2500) were used, respectively.