Figure 4.

Phenotypic diversity in tumors arising from CD44⁺CD24^−/lowLineage⁻ cells. The plots depict the CD24 and CD44 or ESA staining patterns of live human Lineage⁻ cancer cells from T1 (a, c, and e) or T2 (b, d, and f). T1 CD44⁺Lineage⁻ cells (a) or T2 Lineage⁻ cells (b) were obtained from tumors that had been passaged once in NOD/SCID mice. ESA⁺CD44⁺CD24^−/lowLineage⁻ tumorigenic cells from T1 (c) or CD44⁺CD24^−/lowLineage⁻ tumorigenic cells from T2 (d) were isolated and injected into the breasts of NOD/SCID mice; e and f depict analyses of the tumors that arose from these cells. In both cases, the tumorigenic cells formed tumors that contained phenotypically diverse cells similar to those observed in the original tumor.