Fig. 2.

Comparison of affinities of GRP, NMB, peptide #1, MK-5046, and Bantag-1 for cells containing hNMB-R and hGRP-R. Two different cell lines were used to assess human GRP-R interaction: hGRP-R–transfected Balb 3T3 (0.15 × 10⁶ cells/ml) (C) and HuTu-80 native hGRP-R cells (0.25 × 10⁶) (D). For hNMB-R interaction, hNMB-R–transfected Balb 3T3 (0.03 × 10⁶ cells/ml) (A) and NCI-1299 transfected cells (1 × 10⁶) (B) were used. The cells were incubated with 50 pM ¹²⁵I-[d-Tyr⁶,β-Ala¹¹,Phe¹³,Nle¹⁴]Bn-(6–14) for 40–60 minutes at 21°C in 300 μl of binding buffer either alone or with the indicated peptides, and the saturable binding was determined as described under Materials and Methods. The results are expressed as the percentage of saturable binding without unlabeled peptide added (percentage control). The results are the mean ± S.E.M. from at least four experiments, and in each experiment the data points were determined in duplicate.