Further comparison of piR-4447944 and piR-4419185 levels in various prostate-derived cell lines showed that piR-4419185 was expressed at significantly lower levels in all PCa cells than in non-malignant RWPE-1 cells, but the expression level of piR-4447944 in AR+ PCa cells was significantly higher than that in RWPE-1, and was comparable to RWPE-1 cells in AR- PCa cells (Figure 1E). This evidence concerns the gene PIR and posterior cortical atrophy.