Figure 1

Isolation and re-analysis of low (B) and high (C) EGFR expressing subpopulations of the breast cancer cell line MDA-MB-468 CD44+/CD24 -/LOW (A). Isolation was done using a FACSVantage SE flow cytometer (Becton Dickinson). A primary gate (I; R3) based on physical parameters (forward and side light scatter, FSC and SSC, respectively) was set to exclude debris and cell aggregates. Two additional gates (II; R1, R2) were set discriminating clearly a high- from a low-level EGFR-expressing population. The analysis was performed using CELLQUEST software (Becton Dickinson). Insert: Western blotting showed that used MDA-MB-468 clone was positive for CD44 and negative for CD24 which is in agreement with the stemness cell line Hs578t. The same findings could be shown for the two isolated MDA-MB-468 subclones with low high egfr copy numbers. Other used breast cancer cell lines like MCF-7, BT 20, BT 474 and SKBR 3 did not show this phenotype irrespective of their EGFR expression.