CRE(CMe)KA-NW homing to 22Rv1 tumors. Mice bearing orthotropic 22Rv1 xenograft tumors were injected intravenously with 200 μg of FAM-labeled CRE(CMe)KA or 5 mg of iron per kilogram of nanoworms coated with FAM-CRE(CMe)KA. The peptide was allowed to circulate for 3 hours, and nanoworms were allowed to circulate for 5 hours. The mice were then perfused through the heart with PBS, and the tumors were collected. Tumor sections were stained with CD31 or anti-fibrin(ogen) (red) and examined by confocal microscopy. Nanoworms are green; nuclei were stained with DAPI (blue). Bars represent 200 μm. n = 3.