PTEN and neoplasm: To determine if EphB4 expression is regulated by PTEN loss-of-function and activation of the PI3K pathway, we used a conditional knock out of PTEN in prostate epithelium using androgen responsive probasin-Cre, PTENf/f and monitored tumor real time using probasin driven luciferase (cPTEN−/−L) reporter [32, 37].