UDP-glucose dehydrogenase ( UGDH )-specific siRNA suppressed glycosaminoglycan (GAG) synthesis in human articular chondrocytes. Human articular chondrocytes were treated with UGDH-specific siRNA for 48 h. Then, mRNA and the protein level of UGDH were detected using real-time PCR (A) and western blotting assay (B, C), while GAG content of these chondrocyte cultures were detected with 1,9-dimethylmethylene blue dye (D) and Alcian blue dye (E, F). The protein level of UGDH was presented as gray level of the blots quantified using Quantity One software (Version 4.6, Bio-Rad). Values are presented as mean ± standard error of the mean from at least three independent experiments. *P <0.05 and **P <0.01 versus control.