OPRL1 and cancer: Moreover, a possible involvement of the NOP receptor in cancer‐induced bone pain has been suggested by the efficacy of cebranopadol, a mixed opioid/NOP receptor agonist (Linz et al., 2014), and buprenorphine, a mixed μ‐opioid peptide/NOP partial agonist and κ‐opioid peptide/δ‐opioid peptide antagonist (Gastmeier & Freye, 2009) in rats.