The present invention relates to compositions and methods for the selection and use of surface exposed epitopes. The present invention includes in vivo and in vitro phage peptide diplay methods for the identification and selection of peptides and peptide associated factors with desired properties (e.g., targeting specificity, stability, etc.). The present invention further provides methods and compositions for the isolation and identification of peptide-specific antibodies. The present invention also includes methods and compositions employing nuclear localization signals for enhanced nuclear transport and expression of DNA.