AR and posterior cortical atrophy: To determine whether the Sam68-dependent increase in exon 3b expression translated into an increase in endogenous AR-V7 mRNA and protein expression in vivo, we employed the full-length AR- and AR-V7-expressing CWR22 and VCaP PCa cell lines12, which express KHDRBS1 mRNA or Sam68 protein at similarly high levels to other common PCa cell lines (Supplementary Figure S1A and B).