Somatostatin-28 (1-14) is an N-terminal fragment of the neuropeptide somatostatin-28. Somatostatin 28 arises from the posttranslational cleavage of prosomatostatin, which in turn is derived from a large precursor, preprosomatostatin.

L-803087 is a potent and selective agonist of the growth inhibitor sst4 receptor with a Ki value of 0.7 nM for sst4, demonstrating over 280-fold selectivity compared to other growth inhibitory receptors.

CYN 154806 (TFA) is a cyclic octapeptide and an effective selective somatostatin sst2 receptor antagonist. For the recombinant sst2, sst1, sst3, sst4 and sst5 receptors, the pIC50 values are 8.58, 5.41, 6.07, 5.76 and 6.48, respectively.