TRPV1 and bone neoplasm: In mice, inhibiting the osteoclast proton pump (V-ATPase) with an inhibitor of H+ secretion, bafilomycin A1, reduced pain behaviors in mice inoculated with intratibial multiple myeloma cells or Lewis lung cancer (LLC) cells, suggesting that the V-ATPase contributes to bone cancer pain.36,88 Moreover, mice lacking TRPV1, a nonselective cation channel expressed in nociceptive neurons that can be activated by heat, capsaicin, and protons,80 exhibited reduced LLC-induced bone cancer pain compared with WT mice.88