P190B transgene expression does not affect tumor differentiation, proliferation, growth rates, or apoptosis. (a) H&E stained tumor sections (400× magnification) demonstrate that p190B does not alter differentiation of MMTV-Neu tumors. Representative images of immunostaining to detect BrdU incorporation and cleaved caspase 3 (200× magnification) in 5 μm tumor sections from rtTA/Neu and p190B mice are shown. (b) Growth curves of p190B and rtTA/Neu control tumors are graphed. No statistical differences were detected in tumor growth rates (t test, P > 0.05). Error bars represent the standard error of the mean. (c) Quantification of BrdU incorporation shows that exogenous p190B expression does not affect tumor cell proliferation rates (t test, P > 0.05). (d) Cleaved caspase 3 (CC3) immunostaining is quantified and demonstrates that p190B transgene expression does not affect tumor cell survival (t test, P > 0.05). Error bars represent the standard error of the mean.