PCNA and neoplasm: Finally, by observing that the overexpression of DNMT1 and/or UHRF1 did not suppress the oncogenic effect of the pUP plasmid (i.e. of the disruption of the DNMT1/PCNA/UHRF1 interactions), our data reinforce the idea that the integrity of the DNMT1/PCNA/UHRF1 complex is crucial in the tumor transformation.