PTEN and neoplasm: Apc, Keap1, Lkb1, and Pten were not detectable in the majority of developing tumors at endpoint, confirming successful genomic targeting of the tumor suppressors on the protein level (targeting efficacy as assessed by IHC: Apc: 80%; Keap1: 89%; Lkb1: 86%; Pten: 95%, Figure 4E).