Osteoblasts secrete Cxcl9 to regulate angiogenesis in bone.

Bone development and vascularization are coupled events that share many molecular mechanisms. Here the authors identify osteoblast-secreted Cxcl9 as an inhibitory regulator of angiogenesis and osteogenesis, and show that mTORC1 signaling and STAT1 are critical upstream mediators of the cytokine expression.