In these studies, E2F1 expression was only slightly or not significantly induced in tumor tissue relative to matched normal tissue (Fig 6C, 6E and 6G), with the only exception being the invasive breast cancer study in which a 2.16-fold up-regulation of Pak1 correlated with a 2.7-fold up-regulation of E2F (Fig 6I). Here, PAK1 is linked to neoplasm.