Cd1 022

All animal procedures were performed according to protocols approved by the Johns Hopkins University Animal Care and Use Committee, and in accordance with the AAALAC recommendations for the proper use and care of laboratory animals (protocol MO18M129, renewed as MO21M127). Four to six week old female Nude (002019), or CD1 (022) or C57BL6 (027) mice were purchased from Charles River, USA. Isoflurane anesthesia was used during imaging. The health conditions and/or criteria under which early euthanasia was implemented included, but are not limited to, general signs of distress such as hunched posture, lethargy, anorexia, dehydration, rough hair coat and/or those that are directly related to the experimental procedures e.g. loss of weight >10%, lethargy, restricted movement of limbs, distended abdomen or when the bioluminescence signal reaches 10⁹ p/s/cm²/sr. Palpable intraperitoneal tumor or subcutaneous tumors of 1cm diameter or greater detected by inspection and digital calipers also trigger euthanasia. Animals in distress were euthanized by carbon dioxide asphyxiation, and cervical dislocation was used to ensure death. This is an acceptable form of euthanasia for mice and in compliance with the recommendations of the Panel on Euthanasia of the American Veterinary Medical Association.