Figure 1.

Hypoxia increases the proliferation of human pulmonary artery smooth muscle cells (HPASMCs), and induces the expression of forkhead box M1 (FoxM1). Cells were plated at an equal density and exposed to normoxia (N) or hypoxia (H) for 12, 24, or 48 hours (h). Cell lysates and total RNA were used to perform Western blot analyses, probing for the protein expression of proliferating cell nuclear antigen (PCNA) (A) and FoxM1 (C), and to perform quantitative RT-PCR for the measurement of FoxM1 mRNA levels (D). Cell proliferation was measured by the incorporation of bromodeoxyuridine (BrdU) at 24 and 48 hours (B). (E) FoxM1 promoter activity was measured by a Luciferase reporter assay at 24 hours of normoxia or hypoxia. Representative blots are shown, and the gray density of the blots was quantified and is presented in the graphs. Data are expressed as mean ± SEM (n = 3). *P < 0.05. ^#Significantly different between normoxic and hypoxic groups.