passages.id: split_5_test_2922_passage
passages.type: progene_text
passages.text: Transient expression of dominant - negative form of STAT1 ( DN STAT1 ) markedly inhibited STAT1 activation and then alleviated cytolysis activity of IFNalpha - treated YT cells , which was correlated to a markedly down - regulated expression of IRF-1 , a key transcription factor necessary for cytotoxicity of IFNalpha / beta - activated NK cells .