Hemorphins are endogenous peptides belonging to the family of atypical opioid peptides released from hydrolyzed hemoglobin. VV-hemorphins and LVV-hemorphins preferentially interact with delta and kappa receptors, therefore playing the roles of endogenous opiate peptide in vivo. VV-hemorphin-5 has been shown to have antitumor effect both in vitro and in vivo.H-Val-Val-Tyr-Pro-Trp-Thr-Gln-OH or H-VVYPWTQ-OH