Figure 3

Kinetics of PAI-1 expression and secretion under hypoxia. A, B: Quantitative determination of PAI-1 levels in BHY (A) and FaDu (B) cell lysates by ELISA. Cells incubated 24 h under normoxia were chosen as the normoxic standards for PAI-1 expression studies and hypoxic values were calculated relative to these values (BHY: 33.5 ng/mg protein; FaDu: 8.6 ng/mg protein). Mean values ± S.E.M. of four independent experiments, each analyzed in duplicate, are shown. Associated significance of the hypoxic samples vs. the normoxic standard is indicated (*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001). C, D: Quantitative determination of PAI-1 secretion levels in cell culture supernatants from BHY (C) and FaDu (D) cells by ELISA. The PAI-1 secretion level after 24 h normoxia was chosen as the normoxic standard (= 1) and all other values were calculated relative to this value (BHY: 706.5 ng/mg protein; FaDu: 112.8 ng/mg protein). Mean values ± S.E.M. of at least four independent experiments, each analyzed in duplicate, are shown. Associated significance between the hypoxic sample and the corresponding normoxic sample (2 – 24 h) is indicated (*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001).