Although it is worthwhile to mention, that the high bone mass and decreased osteoclastogenesis phenotype of Ccl2-deficient mice has been reported in three independent studies (55–57), the impact of the CCL2/CCR2 axis for human bone remodeling, osteoporosis, cancer metastases, and/or osteolytic bone destruction remains to be established. This evidence concerns the gene CCR2 and cancer.