In vivo tumor growth of control or Shb-overexpressing PC3cells. A. Cells were injected subcutaneously into female nu/nu mice. Tumor growth was carefully monitored. The tumor take rate was 6/10 for the control PC3 cells and 3/10 for the Shb-overexpressing PC3 cells (clone 14). All PC3-Shb tumors regressed when they reached a size of 14, 50 and 170 mm3, respectively. Means tumor volume ± SEM are given. Arrows indicate sacrifice of mice due to the tumor size approaching 1 ml in the controls or in the Shb case tumor regression. * indicates p < 0.05 when tested against control using a Mann-Whitney U-test. B. PC3 control or PC3-Shb tumor cell morphology after staining for Hematoxylin-Eosin (HE), active caspase 3 or Ki-67. A negative control for active caspase 3 staining is also shown. Arrows indicate cells positive for caspase 3. Original magnification was 100× for HE and 400× for Ki-67 and caspase 3. Horizontal bars in subpanels indicate 50 μm. C. PC3 control or PC3-Shb tumor cell apoptosis or proliferation after staining for active caspase-3 or Ki-67. Percentage cells positive for active caspase-3 are given. Means ± SEM for 6 or 3 observations, respectively. * indicates p < 0.05 with a Student's t-test. Tumor cell DNA synthesis by Ki-67 staining. Percentage Ki-67 positive cells are give as in C. ** indicates p < 0.01 with a Student's t-test.