The induction of NDRG1 gene expression by hypoxia and its mimetics. A) A549 cells were exposed to normoxia (20% O2, control) for 20 hours or to hypoxia (0.5% O2) for the time periods indicated in the figure. 15 μg of total RNA was isolated and subjected to a Northern blot analysis as described in 'Methods' section. The blot first hybridized with NDRG1 probe (top panel), and then the membrane was stripped and rehybridized with actin probe (bottom panel) to show loading. B) A549 cells were exposed to 0.5 mM NiCl2 (Nickel), 200 μM CoCl2 (Cobalt), 200 μM desferrioxamine (DFX), or hypoxia (0.5% O2) for 20 hrs. 40 μg of whole cell protein extracts were loaded into each lane and subjected to Western blot analysis as described in 'Methods' section, using antibody against Ndrg1. Bottom panel (actin) shows loading. C) A549 cells were first exposed to hypoxia (0.5% O2) for 20 hrs, then taken out of hypoxic chamber and incubated additionally for the time periods indicated under normoxic (20% O2) conditions. Western blot analysis with antibody against Ndrg1 was carried out in whole cell protein extracts. Bottom panel (actin) shows loading.