MMP7 and posterior cortical atrophy: Given the intersecting co-localization and statistical correlation of perlecan and its degrading protease MMP-7 in tissues, we next sought to determine if perlecan fragments potentially created by MMP-7 lysis of perlecan substrate in tissues could be detected in the serum of the same PCa patients and in serum of additional patients for whom we had serum collected at time of prostatectomy.