HIF-1α siRNA and TPT inhibit bFGF mRNA and protein accumulation. (A-B) HUVECs transfected with the indicated siRNA were seeded on Matrigel in GF^– medium and cultured under normoxic or hypoxic conditions for 16 hours in the presence or absence of TPT (0.5 μM). Expression of bFGF mRNA (A) was determined by real-time PCR (expressed as fold increase relative to untreated cells), while bFGF protein production (B) was measured in supernatants as described in “Material and methods.” (C-D) HUVECs seeded as in panel A were cultured either under normoxic or hypoxic conditions for 8 and 16 hours (C) or in the presence or absence of increasing concentrations of TPT (1 to 1000 nM) for 16 hours (D). Production of bFGF protein was measured in the supernatants as described.