Figure 1.

Some cellular targets for molecular imaging. Oncologic molecular imaging agents exist for each of these targets. In addition to standard imaging agent binding to extracellular targets in the membrane, eg, G-protein–coupled receptors, some agents localize to various organelles, such as lysosomes, mitochondria or golgi apparatus, based on electrostatic potential or pH. PPI , protein–protein interactions, as detected by split luciferase reporters.