Cells reside in specialized microenvironments or niches that profoundly influence cellular function. Therefore, elucidating the molecular and cellular mechanisms that govern the interactions between the niche its cellular constituents is critical for understanding tissue development and function. Using a combination of in vivo mouse models and in vitro cell culture systems, our lab studies how low oxygen tension (hypoxia), in the bone microenvironment influences bone homeostasis, hematopoietic development, and metastatic bone colonization. Our ultimate goal is to develop novel therapeutic strategies to protect against aging associated disorders of the bone and to prevent metastatic dissemination to the bone.