MYC and posterior cortical atrophy: Since purine biosynthesis appears to be a purely MYC-dependent pathway in androgen-responsive PCa cell lines without involvement of the AR, we hypothesized that combining either an inhibitor of androgen biosynthesis (Abiraterone) or a next-generation anti-androgen (Enzalutamide/MDV3100) with either siRNA against IMPDH2 or MPA would increase response to these drugs.