Future work is required to elucidate the underlying mechanism of this phenomenon, but it is likely that IGF2-mediated increased uptake into smooth muscle cells of the TM through high-affinity binding to the CI-M6P/IGF2R, or a similar mechanism mediate by the ApoE2 tag and its cognate receptors, might play a role (as previously shown in MPS II fibroblasts and bEND.3 cells15). Here, IGF2 is linked to mucopolysaccharidosis type 2.