In vivo study, pharmacological intervention with Sphingosine kinases (SPHK) antagonist SKI II or biological inhibition with SPHK1 and SPHK2 short hairpin RNA significantly reduced S1P production and rescued the obese breast cancer-bearing mice from doxorubicin-induced bone loss, manifested by the decreased osteoclastogenesis and recovered bone microarchitecture. This evidence concerns the gene SPHK1 and breast cancer.