Figure 3.

Immunostaining for c-kit. Panels A and B: c-kit is expressed in the cytoplasm of luminal epithelial cells (arrows) and mast cells (arrowhead) present in the stroma of control F344 and wild type rat mammary glands. Panel C: c-kit is not expressed in a mammary tumor obtained from a control F344 rat. Panel D: as expected, Ws/Ws rats do not express c-kit. Counterstaining: Harris' hematoxylin. Ws/Ws: c-kit null rats. Scale bar: 50 μm