Induction of ATF-4 by anoxia correlates with the induction of GADD153/CHOP10 but not with that of HIF-1α. (A) Indicated MDA-MB breast cancer cells were incubated under normoxic, hypoxic, or anoxic conditions for 16 hours and were analyzed by immunoblot for the steady state levels of the indicated proteins: ATF-4, GADD153, HIF-1α, and β-tubulin (as an internal control). (B) MDA-MB435 cells were incubated under anoxia for various times, as indicated, and were analyzed by immunoblot for the indicated proteins. Cells from normoxic conditions were included as a control. N indicates normoxia; H, hypoxia; A, anoxia.