Immunohistochemistry (IHC) using an antibody for peripherin, one of the molecular markers for SNs 20, together with tartrate-resistant acid phosphatase (TRAP) staining, revealed that the peripherin+ SNs (Fig. 1D, black) innervate within the 4T1 tumor in close proximity of TRAP+ osteoclasts (Fig. 1D, black arrows), suggesting that SNs and osteoclasts establish spatial and functional interactions. Here, ACP5 is linked to neoplasm.