Reduced activation of HIF-1α downstream target genes in Psen1-/- fibroblasts treated with cobalt chloride. Psen1+/+ (wt) or Psen1-/- fibroblasts were treated with cobalt chloride for the indicated times (hours). Levels of Vegf (A) and Glut-1 (B) RNA were determined by qPCR (n = 9 cultures per group untreated; n = 3 per group treated). (*) indicates p < 0.05 and (**) p < 0.01 vs. untreated control by Dunnett's post-test. Statistical comparisons between groups are discussed further in the text.