The route of systemic administration, whichis typically intravenousinjection via caudal vein in mice models, leads to an initial depositionof nanoparticles in the liver where the capillary circulation pathsfacilitate the capture of (macro)molecules by resident phagocytes.33 In the breast cancer model used, the liver possessedincreased numbers of myeloid cells with elevated FRβ. Here, FOLR2 is linked to breast carcinoma.