CCAAT/enhancer-binding proteins (C/EBPs) are a family of basic leucine zipper (bZIP) DNA binding proteins that play important roles in normal cellular differentiation and function in a variety of tissues. The C/EBP family is critical for innate immunity and inflammatory response, and consists of five core members: C/EBPalpha, C/EBPbeta, C/EBPdelta, C/EBPgamma, and C/EBPepsilon. Among these proteins, C/EBP beta is usually highly expressed in liver, intestine, lung and adipose. C/EBP beta has three isoforms, two activator, (LAP* and LAP) and a repressor (LIP). These isoforms are differentially translated from the same mRNA. The expression of these isoforms is developmentally and hormonally regulated.