Apt-QLs delivered siRNA molecules labeled with fluorescein isothiocyanate (FITC-siRNA) more efficiently to EGFR-positive MDA-MB-231 breast cancer cells (MFI 185) than to EGFR-negative MDA-MB-453 breast cancer cells (MFI 21) (Fig. 3a). The gene discussed is EGFR; the disease is breast cancer.