C/EBP beta (also known as CCAAT/enhancer-binding protein beta, interleukin 6-dependent DNA-binding protein, and nuclear factor of interleukin 6 [NF-IL6]) is a member of the basic leucine zipper C/EBP transcription factor family. C/EBP has three isoforms that include C/EBPbeta, LAP, and LIP (35 kD, 32 kD, and 20 kD, respectively). This protein is localized in the nucleus and functions as a transcription factor in immune, inflammatory, acute-phase, cytokine, collagen type I gene expression. It is upregulated by growth hormones and has been shown to interact with CEBP-alpha, CEBP-delta, CEBP-gamma, CEBP-epsilon, and CEBP-zeta. The C/EBP beta protein is known to be modified by phosphorylation and ubiquitination. The A16 monoclonal antibody has been shown to be useful for Western blotting of the mouse 35 kD and 32 kD LAP C/EBP beta isoform.