STAT3, activated by IL6 signaling cascade, is necessary for CEBPB transcription, but direct binding of STAT3 to the CEBPB promoter has not been demonstrated (Niehof et al. 2001). As CEBPB activates IL6 transcription in response to oncogenic RAS signaling, and IL6 activates CEBPB transcription (Niehof et al. 2001, Kuilman et al. 2008, Lee et al. 2010), a positive feedback loop exists between CEBPB and IL6.