LPS increases HIF-1α protein expression. (A) Primary mouse bone marrow-derived macrophages or NR8383 cells were rendered quiescent by FBS deprivation for 16 hours. Cells were then maintained either under control conditions (20.8% oxygen) or under hypoxic conditions (1% oxygen) or in the presence of LPS (1 μg/mL) for 6 hours. (B) Quiescent NR8383 cells were maintained under control conditions or in the presence of different concentrations of LPS for 6 hours. (C) Quiescent NR8383 cells were maintained under control conditions, in the presence of LPS (1 μg/mL) or under hypoxic conditions for different periods of time of up to 8 hours. Total cell extracts (25 μg) were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE; 8% gel) and immunoblotted using an anti-HIF-1α antiserum or an antiphospho-p44/p42 MAPK monoclonal antibody.