Figure 3.

Ligand-binding specificity of [Tyr⁴]BN binding. Competition for binding of radiolabeled [Tyr⁴]BN to membrane fractions of human SCLC H-128 tumors was determined in the presence of increasing concentrations of EGF (▴), human growth hormone-releasing hormone (▴), somatostatin (▴), [D-Trp⁶]-luteinizing hormone-releasing hormone (▴), NMB (▿), [Tyr⁴]BN (⋄), RC-3095 (•), and GRP(14–27) (▪). One hundred percent specific binding is defined as the difference between binding in the absence and in the presence of 10⁻⁵ M [Tyr⁴]BN. Each point represents the mean of at least three experiments, each performed in duplicate.