Runx1^P1N/P1N mice have normal numbers of mast cells in multiple anatomic sites. (A) Cells from peritoneal lavage fluid were stained with anti-mIgE and anti–c-Kit mAbs. Data shown are from 1 of 5 independent experiments, each of which gave similar results. The numbers of peritoneal mast cells are shown as means + SD. ns indicates not significant (P > .05). (B) Toluidine blue staining for mast cells (some indicated by solid arrows) in 4-mm-thick paraffin sections of ear pinnae from WT (top) and Runx1^P1N/P1N mice (bottom). The numbers of mast cells in the ear pinnae, back skin, or stomach are shown as means + SD. ns indicates not significant (P > .05).