Fig. 3. Quantification of phosphoglycerate kinase-1, glucose transporter-1 and VEGF mRNA levels in wild-type and HIF-1-null chondrocytes. Chondrocytes were exposed to either 0.5% or 20% oxygen for 22 hours. (A) Bars represent the severalfold changes in PGK-1 mRNA levels compared with wild-type chondrocytes under normoxia (onefold expression). (B) Bars represent the severalfold changes in Glut-1 mRNA levels compared with wild-type chondrocytes under normoxia (normoxic expression taken as 1.0). (C) Bars represent the severalfold changes in VEGF mRNA levels compared with wild-type chondrocytes under normoxia (onefold expression). Data are given as means ± standard deviations (triplicates from three independent experiments). 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.