As controls, we injectedPIC retrovirus into stop-flox luciferase mice with wild type Pten and p53 andCre-only retrovirus (no PDGF) into Ptenf/f; p53f/f mice.No luciferase signal was ever detected in the control mice (data not shown), andnone of the control mice ever developed tumor related morbidity (Figure 1A). Here, PTEN is linked to neoplasm.