Table 2.
Tumor formation ability of sorted cells
| Tumors/injections
|
|||
|---|---|---|---|
| 8 × 105 | 5 × 105 | 2 × 105 | |
| Passaged T1 | |||
| CD44− | 0/2 | 0/2 | — |
| CD44+ | 2/2 | 2/2 | — |
| B38.1− | 0/2 | 0/2 | — |
| B38.1+ | 2/2 | 2/2 | — |
| CD24+ | — | — | 1/6 |
| CD24− | — | — | 6/6 |
| Passaged T2 | |||
| CD44− | 0/2 | 0/2 | — |
| CD44+ | 2/2 | 2/2 | — |
| B38.1− | 0/2 | 0/2 | — |
| B38.1+ | 2/2 | 2/2 | — |
| CD24+ | — | — | 1/6 |
| CD24− | — | — | 6/6 |
Cells were isolated by flow cytometry as described in Fig. 1 based on expression of the indicated marker and assayed for the ability to form tumors after injection into the mammary fat pads of NOD/SCID mice at 8 × 105, 5 × 105, and 2 × 105 cells per injection. For 12 wk, mice were examined weekly for tumors by observation and palpation; then all mice were necropsied to look for growths at injection sites that were too small to palpate. The number of tumors that formed and the number of injections that were performed are indicated for each population. All tumors were readily apparent by visual inspection and palpation except for tumors from the CD24+ population, which were detected only upon necropsy.