CA9 and posterior cortical atrophy: The results showed that the CA-activity/mg protein found in exosomes isolated from PCa plasma (2.9 ± 0.4) was 2.4-fold higher as compared to exosomes purified from CTR plasma (1.2 ± 0.2) (p < .0001) (Figure 4); thus supporting that the increased CA IX expression in plasmatic exosomes of PCa patients was consistent with a real enzyme activity up-regulated in PCa plasma exosomes.