STL-6014 accumulation in the necrotic area of large orthotopic MDA-MB-231-RFP tumors. CD-1 nude, female mice (n = 3) bearing an orthotopically grafted, large MDA-MB-231-RFP tumor were intravenously injected with 15 mg/kg STL-6014. Whole-body and excised tumor images were taken at 4 hours, 16 hours, and 3 days post-injection. Upper panels - in vivo images, lower panels - images of excised tumors. (a and d) Color photos. (b and e) Red fluorescence images for detection of tumor location and size. (c anf f) near infrared (NIR) fluorescence images for detection of STL-6014 distribution. All other details are as described in the methods section. ND, necrotic domain, VD, viable domain.