NRTN and osteoarthritis: In 2018, Nencini et al. [16] reported that inflammatory bone pain (associated with skeletal pathology, including bone cancer, osteomyelitis, osteoarthritis, and fracture) was associated with the activation and sensitization of peptidergic neurons through the ARTN/GFRA3 signaling pathway and non-peptidergic neurons through the GDNF/GFRA1 and NRTN/GFRA2 signaling pathways.