p14ARF depletion abrogates G1 arrest after DNMT1 depletion. A) Real time RT-PCR revealed transcript levels of DNMT1 and p14ARF in siDNMT1 and siDNMT1/p14ARF IMR90 cells in comparison with control cells. B) Real time RT-PCR revealed that p21waf1-Cip1 was not transactivated in absence of p14ARF after DNMT1-depletion in IMR90 cells at 72 hours. C) Top panel: histogram showing proliferation of IMR90 siDNMT1/p14ARF cells in comparison to control cells. Bottom panels: cytofluorimetric profiles of IMR90-siDNMT1/p14 cells stained with Propidium Iodide (PI) as indicator of DNA content, which revealed no significative difference on cell cycle progression in comparison to control cells. IMR90-sip14 cells were used also as a control.