LiCl inhibits the development of myeloma bone disease in vivo. Bone mineral density is significantly increased in 5TGM1 myeloma–bearing mice following treatment with LiCl (A). Histomorphometric analysis demonstrated an increase in trabecular bone volume (B), a decrease in osteoclast number (C), and an increase in osteoblast number (D) in 5TGM1 myeloma–bearing mice following treatment with LiCl. Histologic sections of tibiae from non–tumor-bearing mice, 5TGM1 myeloma–bearing mice, and 5TGM1 myeloma–bearing mice treated with LiCl demonstrated increased osteoclasts lining the trabecular bone surface in 5TGM1 myeloma–bearing mice, and a reduction in osteoclast number in myeloma-bearing mice treated with LiCl. Osteoclasts were identified by TRAP staining. Original magnification, ×200. (E). Immunohistochemistry demonstrated an increase in β-catenin expression in osteoblasts lining the bone surface in myeloma-bearing mice treated with LiCl compared with control. Original magnification, ×400 (F). Treatment with LiCl significantly reduced serum IgG_2bκ concentrations in 5TGM1 myeloma–bearing mice (G). Data are expressed as means (± SEM). *P < .05 compared with nontumor control. †P < .05 compared with 5TGM1 control.