Fig. 3

The ex vivo hypoxic tumor cells possess properties functionally associated with self-renewal and tumorigenic potentials. Tumor cells are enzymatically dissociated and isolated from the MDA-MB-231/HRE-EGFP xenografts. After sorting into the enhanced green fluorescent protein (EGFP)⁺ and EGFP⁻ populations, tumor cells were plated for in vitro assays (a-c) or directly re-implanted in athymic mice (d). Detailed experimental conditions are described in “Methods”. a Clonogenic potential (n = 6, ***p < 0.001, Student’s t test). b Tumor cell invasion (n = 3, *p < 0.05, Student’s t test). c Wound healing potentials (n = 5, *p < 0.001, Student’s t test). d Tumorigenic potentials in vivo are primarily reflected by percent tumor take (the ability of implanted cells to produce a tumor)