Diesel exhaust exposure on gene expression of HIF-1α, PHD2, and VEGF. A) Gene expression in confluent HUVECs treated with different concentrations of DEP (0, 5, 15, 30 μg/ml) for 4 hours in vitro. B) Gene expression in the ischemic hindlimb skeletal muscles exposed to WDE or FA for 2, 5 and 8 weeks. Data are expressed as fold change over the group exposed to FA for 2 weeks. AW2, AW5, or AW8, groups exposed to FA for 2, 5 or 8 weeks; DW2, DW5, or DW8, groups exposed to WDE for 2, 5 or 8 weeks. *p<0.05 vs. control (0 μg/ml); **p<0.001 vs. 0 μg/ml; +p<0.05 vs. 15 μg/ml; #p<0.05 vs. 5 μg/ml. N = 8.