EGFR and breast cancer: In view of our findings that GD3 associates with EGFR in breast stem-like cancer cells (Figure 4) and in GD3S-overexpressing breast cancer cell lines (Figure 5), and that GD3S expression enhances malignant potential of breast cancer cell lines (Figure 1 and 2), we hypothesized that a combination of gefitinib treatment and GD3S knockdown may be an effective therapeutic strategy to combat breast cancer.