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FIGURE 1. (A) Presence of displayed 
-MSH peptide analogs was probed by ability of antibody to C terminus of -MSH peptide to recognize and bind to phage-displayed peptide. Two 1-µL dots of phage solution containing 1011 virions per milliliter were immobilized on 0.2-µm nitrocellulose, and presence of phage particles was demonstrated with antiphage antibody (1:1,000 dilution). Presence of recognizable -MSH peptide was determined with antibody to C terminus of -MSH peptide (1:1,000). Complexes were detected with secondary antibody conjugated to horseradish peroxidase (1:1,500). (B) Ability of displayed peptide to be recognized and bound by MC1 receptor on cultured B16-F1 melanoma cells was determined by micropanning. Suspension of B16-F1 melanoma cells was incubated with bio-MSH2.0 phage or nonbiotinylated MSH2.0 phage at inputs of 108, 107, and 106 TU/mL for 1.5 h on rotator at 37°C. Cells were then extensively washed with PBS, and final wash containing 2.5% CHAPS was used for determination of phage titers with E. coli. Bio = biotinylated.
