MC1R and metastatic neoplasm: We describe herein the design and development of NOTA-based cell-targeting agents having very high affinity and selectivity for the GRPR (Gastrin-Releasing Peptide Receptor), the SSTR2 (Somatostatin Receptor Subtype 2), and the MC1R (Melanocortin-1) receptors that are expressed on the surfaces of many solid, primary human tumors and their metastatic disease.