FIG. 2.

Representative histopathologies of mammary tumors that developed in MMTV-c-rel transgenic mice after multiple cycles of pregnancy and regression. (A) Adenocarcinoma; (B) pulmonary metastasis in a mouse with mammary adenocarcinomas; (C) adenosquamous carcinoma showing areas with extracellular squamous differentiation (arrow); (D) squamous cell carcinoma; (E) spindle cell carcinoma; (F) immunohistochemistry for cytokeratin 8 expression in the spindle cell carcinoma shown in 2E. Note the staining of many of the spindle cells and staining of luminal epithelium in the glands (arrow).