D Cumulative progression into S phase of HeLa cells expressing KEN mutant E2F7/8-EGFP, monitored by nuclear PCNA dot formation. P value indicates significant change of EGFP-positive versus negative cells from the same cell line.E Cumulative cell death of HeLa cells expressing KEN mutant E2F7/8-EGFP, monitored by cell blebbing and cytosolic PCNA-mCherry. 