Molecular Imaging of Aminopeptidase N in Cancer and Angiogenesis

Figure 11

Multivalent targeting of the APN enzyme. (a) Bivalent homotopic targeting agents utilize the same targeting unit to cross-link two adjacent APN enzymes. (b) Bivalent heterotopic targeting agents bind to the APN enzyme and a nearby cell surface receptor. (c) Two-step activated targeting agents are cleaved by the APN enzyme, and then, the product binds a nearby cell surface receptor.

(a)

(b)

(c)