MMP2 and posterior cortical atrophy: Further, prior findings demonstrated that MEK4 positively regulated MMP-2 expression in vitro, that inhibition of MEK4 in vitro decreased MMP-2 and that short term treatment of men with PCa with genistein decreased MMP-2, while having no effect on MEK4. These new findings suggested the notion that prolonged treatment with a chemopreventive agent may induce compensatory changes that alter the biomarker response profile.