At 48 h post-injection (p.i.)of [111In]In-DTPA-trastuzumab Fab-PEG24-EGF bsRICs, subcutaneous (s.c.)SK-OV-3 human ovarian cancer xenografts that were HER2-positive but EGFR-negative, MDA-MB-231 human BC xenografts that were HER2-negative but EGFR-positive, and MDA-MB-231/H2N tumor xenografts that coexpressed HER2 and EGFR were imaged in mice by single photon emission computed tomography (SPECT). The gene discussed is EGFR; the disease is breast cancer.