In light of the observed GD3/EGFR association in breast CSCs and breast cancer cell lines, along with the increased gefitinib sensitivity in GD3S-knockdown MDA-MB468 cells, we propose that GD3S is involved in gefitinib-resistance of EGFR-positive breast cancer cells, and can be considered as a potential therapeutic target in gefitinib-resistant breast cancers. The gene discussed is EGFR; the disease is breast cancer.