PIK3CA, AKT, and FOXO control RB/E2F apoptosis and tumor onset in vivo. A. Newborn CHX10-Cre (+) and CHX10-cre (+); Rb1
−/− retina were electroporated in vivo with CAG-luciferase and control, constitutively active (ca) PIK3CA, ca-AKT plasmids, or dominant-negative (dn) Foxo1. Eyes were harvested at 60 days for H&E and KI-67 staining. B. Newborn CHX10-Cre (−); Rb
−/− mouse retinas were transfected with GFP or Cre:GFP and either control plasmid, or plasmids that express ca-PIK3CA, ca-AKT, or dnFoxo1. Retinas were harvested 2 days post-electroporation, trypsinized into single cells, and sorted into GFP (+) and (−) cells by fluorescence-activated cell sorting (FACS). Individual GFP (+) retinal cells were quantified for TUNEL in triplicate at 48 hours. C. Individual GFP (−) retinal cells (counterparts from 4B) were quantified for TUNEL in triplicate at 48 hours. ***, p < 0.001. Scale bar, 100 μm.