MELK and posterior cortical atrophy: The variability of the gene expression data between healthy donors and PCa patients is depicted in the principal component analysis (PCA) plot in Figure 2A. Half of the upregulated genes (MELK, CDKN3, CDK1, and FOXM1) are associated with cell proliferation functions; these four genes showed more than 5-fold upregulation (Figure 2B).