passages.id: split_4_validation_35_passage
passages.type: progene_text
passages.text: In addition , activation of the promoter by IL-4 was blocked by mutation of all three NF-kappaB sites and similarly reduced by mutation of site 1 , suggesting that NF-kappaB - STAT6 interactions may be necessary for STAT6 - mediated transactivation of the germline gamma1 promoter .