Basal levels of HIF-1α are unchanged in M146V FAD mutant fibroblasts. Shown are prolonged exposures of Western blots from the fibroblast lines studied in Figure 11. In panel A, representative blots are shown of samples from individual cultures harboring the human wild type Psen1 (HuPS1Wt) or the M146V FAD mutant. The lower panel shows the blot reprobed for β-tubulin. In panel B, levels of HIF-1α were determined by quantitative Western blotting (n = 5 cultures per genotype) with the levels of HIF-1α normalized to the levels of β-tubulin. Studies were performed both in the presence of serum (FBS) and after overnight serum starvation (-FBS). There were no statistically significant differences between the HuPS1Wt and M146V FAD mutant cell lines.