[Cell surface proteins that bind somatostatin and trigger intracellular changes which influence the behavior of cells. Somatostatin receptor scintigraphy has been one of the most important diagnostic tools for staging of Neuroendocrine gastrointestinal tumors and also indicating sensitivity to treatment with somatostatin analogues. This marker can be used for diagnosis and follow-up of the patients. (from Ann Oncol 1999;10 Suppl 2:S3-8) ( NCI )]