In a model of bone cancer pain induced by breast cancer, BDNF mRNA and protein in the L3 dorsal root ganglion were significantly increased and were located in small neurons (mainly nociceptive neurons) rather than in medium or large neurons (non-nociceptive neurons), and the expression level of NGF was also increased (Tomotsuka et al., 2014). This evidence concerns the gene NGF and bone neoplasm.