TP53 and neoplasm: Even though PSA-CreERT2-mediated gene inactivation is less efficient in the AP than in the DLP [13], and tumor formation is heterogeneous in this lobe, we detected p16-positive cells in PINs, and observed large sarcomatoid tumors in the AP in about 20% of Pten/Trp53(i)pe−/− mice between 5 and 7 months AGI.