The synthetic targeting peptide SP5-2 (TDSILRSYDWTY), mutant peptide MP5-2 (TDSILRSYDGGG), and control peptide (RLLDTNRPLLPY) [27] were synthesized (Invitrogene, Inc., CA, USA) and purified using reverse-phase high-performance liquid chromatography to .95% purity. Conjugation of these peptides with FITC or biotin was performed through the addition of FITC or biotin to the peptide amino terminus by the same company.