Accumulation of STL-6014 in large and small MDA-MB-231-RFP tumors. CD-1 nude, female, mice bearing orthotopically-grafted MDA-MB-231-RFP tumors were intravenously injected with STL-6014 (15 mg/kg). Fluorescent images of (a and b) large (n = 9) and (c and d) small (n = 10) tumors, were taken at the indicated times post-injection. Upper panels - near infrared (NIR) fluorescence images indicate STL-6014 distribution, lower panels - red fluorescence images indicate tumor size and location. (a) Fluorescence signals in a large tumor over the first nine hours post-administration. (b) Fluorescence signals in the large tumor over the following one to seven days post-administration. (c) Fluorescence signals in a small tumor over the first 9.5 hours post-administration. (d) Fluorescence signals in the small tumor over additional one to three days post-administration. Longitudinal STL-6014 decay curves in representative (e) large and (f) small tumors. Total fluorescence intensity within the individual tumor boundaries, was normalized per unit area and expressed as photon/(sec × cm2). Other details are as indicated in the methods section.