Effects of CoCl2 treatment on HIF-1α expression in mouse astrocytes. (A) The cells were incubated in the presence or absence of 125 μM CoCl2 for 6 hr. HIF-1α mRNA expression was determined by RT-PCR. Each bar represents the mean ± SD of relative density/volumes of the bands on film negatives from at least three experiments. Asterisk and number sign indicate significant difference compared to relevant controls (p < 0.01; one-way ANOVA, followed by multiple comparisons among means). (B) Western blots using nuclear proteins show that both hypoxia (H) and CoCl2 (Co) up-regulated HIF-1α protein in HIF-1α+/+ and HIF-1α+/- cells. There was no HIF-1α protein detected in control cells (C).