To determine whether the peptide sequences displayed on PC5-2 would actually interact with NSCLC cells, we used fluorescein isothiocyanate (FITC)-labeled SP5-2 peptide (FITC-SP5-2) in place of the PC5-2 phage for a peptide-binding assay through immunofluorescent staining. FITC-SP5-2 specifically bound to all of the NSCLC cell lines we tested, including CL1-5, H460, A549, PC13 and H23, but did not bind to NNM. The same concentration of FITC-labeled control peptide (FITC-Con-P) revealed no such binding activity (Fig. 1C) . We also evaluated the magnitude and specificity of SP5-2 binding using flow cytometry. The proportions of CL1-5, H460, A549, PC13 and H23 cells bound by SP5-2 were 43.0%, 45.8%, 44.3%, 20.1% and 44.0%, respectively ( Fig. S3 and Text S2).