Fig. 7. K1014 transgene expression in an SCC of a K1014chim mouse subjected to the DMBA/TPA protocol. (a) SCC tumor cells from the skin stained with antibodies against K10 (green) and BrdU (red). Note that the K1014chim keratin is homogenously expressed throughout the tumor and apparently does not interfere with proliferation as indicated by the K10/BrdU double-positive cells. (b) Histological section of a lung SCC and (c) staining with K10 (green) and BrdU (red) antibodies. Note that the tumor tissue stains for the K1014chim protein. (d) As expected, the SCC was negative for TTF-1 (thyroid transcription factor-1), a marker for normal airway epithelial cells. Note the nuclear staining (white arrows) of normal lung tissue, suggesting that the SCC represents a metastasis of the primary tumor shown in panel a. The dashed line demarcates the border between the tumor and normal lung tissue. The asterisk indicates the bronchus.