KRAS and prostate intraepithelial neoplasia: Distinct stages of disease can be modeled by a series of genetic perturbations in PCa GEMMs including the loss-of-function of Nkx3.1 to recapitulate early PIN (N) [15–18], additional loss of Pten expression to mimic advanced adenocarcinoma (NP) [19], and activation of oncogenic mutant of K-ras (G12D) to mimic metastatic disease (NPK) [20].