Time-dependent modulation of HIF-1α protein expression by A23187 and BAPTA-am. (A) HepG2 cells were incubated under normoxia (16% O2) or hypoxia (8% O2) or treated with A23187 (5 μM) or BAPTA-am (5 μM) under normoxia (16% O2) and then harvested at different time points. HIF-1α protein was detected by Western blot analysis. The expression of HIF-1α under hypoxia at 4 hours was set to 100%. Values are means ± SEM of 3 independent culture experiments. (B) Western blot analysis. Protein (100 μg) from HepG2 cells treated with A23187 (5 μM), BAPTA-am (5 μM), or BAPTA (5 μM) for 4 hours was subjected to Western analysis with an antibody against HIF-1α or β-actin. Autoradiographic signals were obtained by chemiluminescence and scanned by videodensitometry.
