Background: CCAAT/enhancer-binding proteins (C/EBP) consist of a family of transcription factors that play an important role in regulating the balance between cell growth & differentiation. The various isoforms of C/EBP (α,,β,,γ,,δ,,ε,, ζ, ) exhibit similar DNA-binding specificities and contain a leucine zipper dimerization domain (1). A number of serine targets of PKA have been identified in C/EBP-β,, suggesting its activities are post-translationally regulated by cAMP (2). Even though, it has been show that C/EBP β, occurs predominantly as a heterodimer (3), C/EBP β, & γ, readily heterodimerize with each other as well as with C/EBP α, (4). Additionally, 3 isoforms of C /EBP β, can be detected (LAP*, LAP, & LIP) (5).