To investigate the accumulation of LyP-1 in tumor tissues, fluorescein isothiocyanate isomer (FITC) was modified at the N-terminus of peptides, and the FITC-LyP-1 or FITC-control peptide (ARALPSQRSR) was administrated via tail vein to MDA-MB-435 and C8161 xenografts, respectively. The gene discussed is PTPN22; the disease is neoplasm.