PTHLH and neoplasm: The skeleton is a frequent site of breast cancer metastasis.51 Once localized to bone, breast cancer cells release factors, including PTHrP,52 IL-11,53 CTGF,54 and RANKL,55 which increase osteoclast activity, leading to osteolysis and tumor progression.23,56 As such, we examined the ability of mechanical vibration to regulate release of paracrine signals from breast cancer cells.