ISG15 and leukemia: -Sirt2−/− MEF had no IFNβ induced STAT1 activation or expression of ISG (Oasl2 Cxcl10 ISg15, ISg54)-SIRT2 regulated IFNβ induced CDK9-mediated p-STAT1-SIRT2 KD leukemia cells less sensitive to IFNα–mediated antiproliferative effect