Hypoxia-mediated induction of mDia-1 in THP-1 cells and its impact on up-regulation of Egr-1 in THP-1 cells and macrophages. THP-1 cells and Mϕ from mDia-1 DrfI+/+ and DrfI−/− mice were exposed to hypoxia (H; 0.5% of oxygen) or normoxia (N) for the indicated times. A, total protein was prepared from THP-1 cells, and immunoblotting with anti-mDia-1 IgG was performed on 30 μg/lane of protein from THP-1 cells. Results of multiple experiments were quantified. B and C, total RNA was prepared from those cells, and real-time PCR analysis of Egr-1 expression was performed. Data are represented as the relative expression of mRNA for Egr-1 normalized to 18 S rRNA. B, RNA was prepared from THP-1 cells transfected with siRNA-mDia-1 or scramble siRNA and then subjected to hypoxia for 15 min. C, RNA was prepared from DrfI+/+ and DrfI−/− Mϕ after exposure to hypoxia or normoxia for the indicated times. * (p < 0.0001) and ** (p < 0.001) indicate statistical significance; #, no statistical significance.