C/EBP ? is a member of the C/EBP transcription factor family. The C/EBP ? gene encodes several isoforms, which have truncated transcription activation domains by the alternative translational initiation at multipe AUG start sites. Initiation of translation at the in-frame AUGs forms four C/EBP ? isoforms. C/EBP ? is also known as interleukin 6-dependent DNA-binding protein (IL6DBP), liver activator protein(LAP) or liver-enriched transcriptional activator protein transcription factor 5 (TCF5). C/EBP ? contributes to the regulation of the acute phase response in hepatocytes. Stat3 has an important function in IL-6-mediated transcription of the C/EBP ? gene that has direct implication for acute phase response in liver cells.The 35 kDa C/EBP ? form requires phosphorylation for its DNA binding ability, and increased binding of C/EBP ? isoforms during acute-phase reaction occurs through its upregulation and structural modification.