sst binding. Cells were incubated for 2 hours on ice with¹²⁵I-somatostatin (2,000 Ci/mmol) in 24-well plates. A total of 10,000 cpm was added to each well containing 10⁶cells. Cold somatostatin (10⁻⁵ mol/L) competed for binding and specific binding was calculated as total binding minus binding in the presence of cold somatostatin. Data are means ± SD from one representative experiment of three.