TCF4 and posterior cortical atrophy: IHC analyses using adjacent PCa tissue sections revealed positive nuclear staining for transgenic AR and β-catenin, as well as positive staining for phosphorylated IGF1R and for β-catenin downstream targets, including TCF4, c-Myc, Cyclin D1, AXIN2, and Lgr5 (Fig. 5f–m).