EREG and posterior cortical atrophy: Figures 2B, C depict the presence of proepiregulin on the cell surface of all PCa cell lines, but in comparison to LNCaP cells, 22Rv1 (p=0.0043) and LNCaPEnzR (p<0.0001) cells contain more proepiregulin on the cell surface. ELISA was used to determine the EREG concentration in the supernatant (Figure 2D). The results show that no EREG is secreted by LNCaP and 22Rv1 cells. In contrast, DU145 (p<0.0001), PC3 (p<0.0001) and LNCaPEnzR (p=0.027) cells secrete EREG, whereby DU145 cells secrete the highest amount with about 330 pg/ml of mature EREG.