Figure 4

Subcutaneous tumor formation requires activation of PI3K. A. Red fluorescence was used to measure subcutaneous tumor growth. Fluorescence in photons per second per cm² per steradian was normalized to the starting value one week after injection. n = 6; *, p < 0.05. B. Histopathology (H&E stain) and immunohistochemistry show that the tumors were ERα+, Ki67+ adenocarcinomas. The central region in the sections contains an island of mouse stroma surrounded by human tumor cells (PGR gives a non-specific cytoplasmic stain in the stroma). Scale bars 100 μm.