Final answer:
In-111 pentetreotide is an analog to somatostatin, used in medical imaging to diagnose tumors with somatostatin receptors.
Step-by-step explanation:
In-111 pentetreotide acts as an analog to somatostatin. Somatostatin is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G protein-coupled somatostatin receptors. This analog is used in medical imaging to diagnose tumors that have somatostatin receptors, such as neuroendocrine tumors. The process involves radiolabeling the analog with Indium-111 to allow for visualization using nuclear medicine techniques such as SPECT (Single Photon Emission Computed Tomography).