Treatment of colorectal cancer-bearing mice with TNF-α or IFN-γ conjugated to the tumor vascular homing peptide TCP-1 resulted in tumor growth delay, increased TUNEL (terminal deoxinucleotidyl transferase-mediated dUTP-fluorescein nick end labeling) staining in the tumor, and reduced systemic toxicity compared to unconjugated cytokines. The gene discussed is TNF; the disease is colorectal cancer.