Although there is minimal information on the molecular events leading to and during neosis, the enormous data on hand concerning karyokinesis, cytokinesis, nuclear budding, cell cycle checkpoints, cyclins, oncogenes, tumor suppressor genes, genomic instability, apoptosis, mitotic catastrophe, and molecular profiles characterizing their alterations in different cancer types can be exploited to formulate a rational process for understanding the etiology of cancer and developing rational, effective and safe therapies against cancer. This evidence concerns the gene PCNA and cancer.