Figure 2.

Hypoxia promotes cell migration, invasion, and collagen remodeling. (A) MDA-MB-468 cells were added to Transwell chambers, in which the membranes were precoated with FBS (cell migration; n = 21) or in which reconstituted Matrigel was present (cell invasion; n = 10). Studies were performed for 24 h in 21% O₂ (gray bar) or 1.0% O₂ (black bar). Migration and invasion are expressed relative to the levels observed with normoxic controls (mean ± SEM). (B) MDA-MB-468 cells were treated with CoCl₂ or with vehicle. Cells were allowed to migrate for 24 h. Cell migration is expressed relative to that observed with vehicle (mean ± SEM; n = 3). *, P < 0.05; **, P < 0.005. (C) Cells were cultured for 18 h on fluorescein-labeled type I collagen in 21% (normoxia) or 1.0% O₂ (hypoxia). Type I collagen remodeling was assessed. Cell nuclei are stained with DAPI. Bar, 50 μm.