The invention provides a peptide having at least 3 amino acids comprising an amino acid sequence selected from a) X.sup.1SM [SEQ.ID.NO.:1] b) LX.sup.2HK [SEQ.ID.NO.:2] c) PSGX.sup.3ARA [SEQ.ID.NO.:9] d) SX.sup.4RSMNF [SEQ.ID. NO.:16] e) LX.sup.5HKSMP [SEQ.ID.NO.:18] in which X is a basic amino acid residue, X.sup.1 is Q or P, X.sup.2 is A or T, X.sup.3 is an acidic amino acid residue and X.sup.4 is P or Q, the invention further provides non-viral cell-targeting vector complexes and methods associated therewith.