FIG. 1.

Immunostaining for HIF-1α: HIF-1α, if present, was stained green. As a counterstain, cell nuclei labeled with DAPI appear blue. (A) At 20% O₂, there was no significant staining at 96 h in 2D. (B, C) shows cells in 2D at 1% O₂ stained for HIF-1α at 72 and 96 h, respectively. (D, E) HIF-1α staining in 3D. (D1) Immunostaining in 1% at 96 h (D2 is an overlay image). (E1) is the representative image of staining at 20% O₂ at 96 h (E2 is an overlay image). Quantification of HIF-1α–expressing cells (F) from each of the studies (A–E). HIF, hypoxia-inducible factor; DAPI, 4′,6′-diamidino-2-phenylindole; 2D, two-dimensional. Color images available online at www.liebertonline.com/tec