PLXNB1 and Familial prostate cancer: To understand the contribution of the clinically relevant Plexin-B1(P1597L) mutation to prostate cancer progression, we established two lines of mice carrying a targeted insertion of either PLXNB1WT or PLXNB1P1597L cDNA preceded by a flox-STOP-flox cassette into the Rosa26 locus.