FIG. 5.

Nuclear export of HIF-1α occurs in reoxygenated HeLa cells through a pathway that requires nuclear prolyl hydroxylase activity. (A) Hypoxic HeLa cells (panels a to l) were either fixed with 1% formaldehyde or transferred to an oxygenated incubator for 3 or 10 min prior to fixation. Cells were also treated with DMOG (1 mM) for 8 h (panels m to r). Cells were stained with an anti-HIF-1α antibody or with Hoechst. Fields a to c are the same exposure. Fields g, h, i, m, n, and o are also equivalent exposures. (B) Nuclear/cytoplasmic ratios were calculated for ca. 30 cells for each condition obtained from at least three independent experiments. Mean averages with the standard deviations are shown. ✽, data not available since there is no signal.