Fig. 5. Quantification of extracellular matrix expression in wild-type and HIF-1-null chondrocytes. Epiphyseal chondrocytes were cultured under either 0.5% or 20% oxygen for 22 hours. (A) Analysis of aggrecan gene expression: Bars represent -fold changes of aggrecan mRNA levels in HIF-1-null cells compared with wild-type levels. (B) Alcian-blue staining of extracellular proteoglycans. Bars represent means of alcian-blue absorbance ± standard deviations of wild-type and HIF-1-null cultures exposed to normoxia or hypoxia (duplicates from three independent cultures). Data are given as mean ± standard deviations (triplicates from three independent experiments) and statistical differences were calculated as: wild-type normoxia vs HIF-1-null normoxia; wild-type hypoxia vs HIF-1-null hypoxia; wild-type normoxia vs wild-type hypoxia. **P0.01.