E2F2 and neoplasm: E2F2 is the center of the balance between cell proliferation and cell cycle arrest or apoptosis. Activation of deregulated E2F leading to both growth-promoting pathways or tumor suppressor pathways can result in oncogenic changes. If the amount of free E2F is below the threshold, E2F activates only growth-related target genes. However, when the amount of E2F exceeds the threshold, E2F activates not only growth-related targets but also pro-apoptotic targets.