RTN4R and neoplasm: Several tumor-homing peptides, such as the cyclic peptide, NGR (CNGRCVSGCAGRC), have been found in vivo and were used in combination with anti-cancer drugs to increase the anti-tumor activity of these drugs and reduce the toxicity to normal tissues (Arap et al. 1998; Sacchi et al. 2004; Wang et al. 2006).