Figure 4.

Preneoplastic lesions can give rise to tumors in vivo. MAP mice were treated with tamoxifen at 5–6 wk of age and sacrificed when they displayed clinical signs of medulloblastoma. (A) Whole-mount NBT/BCIP staining of brains from these mice showed high levels of AP only in the tumor and not in the normal cerebellum or forebrain. H&E staining (B) and NBT/BCIP staining (C) of tissue sections confirmed that tumors consisted of cells that had been induced to express AP at 5–6 wk. Magnification, 20×.