AR and Familial prostate cancer: While the Ptenfl/flKrasG12V and Ptenfl/flp53fl/fl models used in this study recapitulate alterations in the P13K, Ras/Raf/MEK/ERK, and p53 signaling pathways (32), the effect of mutation of PLXNB1 in a background of other commonly found changes in human prostate cancer, such as AR mutation or amplification, was not assessed here.