RTN4R and neoplasm: Recent research efforts have opened up this field by considering ectoproteases in tumour-targeting strategies such as ectoprotease-targeted prodrugs, where one exploits the catalytic activity of the ectoprotease or ectoprotease-targeted radiotherapy using high-affinity small molecules, small molecules blocking exosites of ADAM17, and MMP2/9, NGR-prodrugs for APN, or mAbs (Table 1) (Figure 3).