Fig. 2.

Knockdown efficiency of p21 siRNA transfection in human normal chondrocytes in response to mechanical strain. The concentration of p21 siRNA was 100 nM. Expression levels of p21, COL2A1, ACAN, MMP3, MMP13, ADAMTS4, and ADAMTS5 mRNAs were quantified by real-time PCR. Values are normalized to GAPDH expression. Columns represent mean ratios with 95 % confidence intervals against untreated and nonloaded control. The results shown are the average of four individual experiments. White columns: untreated samples, Black columns: nonspecific control siRNA samples, and gray columns: p21 siRNA samples. ACAN aggrecan, ADAMTS a disintegrin and metalloproteinase with thrombospondin motifs, COL2A1 collagen, type II, alpha 1, MMP matrix metalloproteinase; PCR polymerase chain reaction, siRNA small interfering RNA