A) Gene expression of scx, bmp4, and tgfb was evaluated in WT mice 24 h after fracture. Expression of scx was upregulated in the fractured limb compared with the contralateral nonfractured limb, whereas bmp4 was downregulated and tgfb unchanged. *P < 0.05, fractured vs. nonfractured limbs for respective gene. B) Immunohistochemistry for GFP on a subset of Scx:GFP mice at d 14 after fracture showed that ScxGFP was evident in the newly formed woven bone and cartilage of the callus, but not in the uninjured, contralateral cortical bone (CB) of the femur. BM, bone marrow.