PARP1 and posterior cortical atrophy: However, the observed increase in PARylation during disease progression cannot be simply attributed to total PARP‐1 protein expression, as the ratios of PARP‐1 and PAR expression levels differed across disease states (Fig 1D, bottom middle; medians of PAR values 51.67, 54.29, and 47.81 for non‐neoplastic, primary PCa, and mCRPC, respectively).