We therefore generated a novel transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse model to investigate the role of Lgr4 in prostate cancer development and metastasis <i>in vivo</i> TRAMP <i>Lgr4</i><sup>-/-</sup> mice exhibited an initial delay in prostate intraepithelial neoplasia formation, but the frequency of tumor formation was equivalent between TRAMP and TRAMP <i>Lgr4</i><sup>-/-</sup> mice by 12 weeks.