Fig. 6. Analysis of type-II collagen expression in normal and HIF-1-deficient chondrocytes. Epiphyseal chondrocytes were cultured under normoxic or hypoxic conditions for 22 hours. (A) Analysis of type-II collagen gene expression. Bars represent -fold changes of type-II collagen mRNA levels in HIF-1-null compared with wild-type chondrocytes (normoxic expression taken as 1.0). Data are given as mean ± standard deviations (triplicates from three independent experiments). (B) Quantification of type-II collagen protein. Bars represent means ± standard deviations (triplicates from three independent experiments, normalized to total protein content). 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. *P0.05; **P0.01.