A cell-growth-on-bead assay was used to screen one-bead, one-compound combinatorial libraries for peptide ligands that attract attachment and growth of human lung cancer cells. A consensus cyclic peptide sequence, D-cys-L-asn-L-gly-L-arg-L-gly-L-glu-L-gln-D-cys (cNGRGEQc), was identified as a ligand for a cell surface receptor, alpha3beta1 integrin. This peptide ligand and its analogs have the potential to be used as diagnostic and therapeutic agents for lung cancer.