OPRK1 and posterior cortical atrophy: Furthermore, our RNA seq and IHC analyses showed an increasing trend of OPRK1 expression as PCa progressed from castration-naïve to castration-resistant diseases, which was consistent with the findings from cultured PCa cells27 and with multiple databases for advanced PCa showing upregulation of OPRK1 in advanced PCa, particularly in those at high risk for death21,25,26.