IGF2R and neoplasm: This might be due to: (1) internalization of 2G11 mAb upon binding to IGF2R as demonstrated by internalization experiments (Fig. 2b); (2) the residualizing nature of trivalent radiometals such as 111In or 177Lu that tend to remain in the tumor even after separating from the mAb, as opposed to 188Re, which leaves the tumors relatively fast after oxidizing into the inert perrhenate anion.