IGF2R and lysosomal storage disease: Many approved enzyme replacement therapy (ERT) regimes for nonneurodegenerative lysosomal storage diseases have exploited the cell surface cation-independent mannose 6-phosphate receptor (CI-MPR) targeting pathway, where mannose 6-phosphorylated glycans present on the ERT enzyme bind avidly to the CI-MPR, resulting in their internalization into clathrin-coated vesicles and delivery to lysosomes of patient cells (10, 11).