Fig. 5. Fluorescence photomicrographs showing colocalization of keratinocytes (red ), mast cells (green ), and neurokinin-1 (NK-1) receptors (blue ) in hind paw skin 4 weeks postfracture. Compared with control animals (A ), the NK-1 receptor expression is up-regulated in dermal mast cells at 4 weeks postfracture (B ). Treatment with LY303870 blocked the accumulation of mast cells and the up-regulation of NK-1 receptors (C ). Scale bar = 50 μm. Fx = fracture; LY = LY303870, NK1R = NK-1 receptors.