The study investigates the role of three members of the C/EBP family of leucine zipper proteins (C/EBPδ, C/EBPβ, and C/EBPα) in the terminal differentiation of 3T3-L1 fibroblasts into adipocytes. Dexamethasone (DEX) and methylisobutylxanthine (MIX) are identified as direct inducers of C/EBPδ and C/EBPβ gene expression, respectively. During the early phase of differentiation, high levels of C/EBPδ and C/EBPβ accumulate, followed by the activation of C/EBPα in the terminal phase. The study demonstrates that precocious expression of C/EBPδ or C/EBPβ accelerates adipogenesis, while preventing their expression blocks terminal differentiation. Retrovirus-mediated overexpression of C/EBPβ and C/EBPδ in NIH-3T3 cells results in their conversion into committed adipoblasts, capable of synchronous and uniform differentiation into fat-laden adipocytes. The findings suggest a hierarchical regulatory cascade involving C/EBP proteins in adipocyte differentiation, with C/EBPδ and C/EBPβ playing early catalytic roles and C/EBPα regulating the final stages.The study investigates the role of three members of the C/EBP family of leucine zipper proteins (C/EBPδ, C/EBPβ, and C/EBPα) in the terminal differentiation of 3T3-L1 fibroblasts into adipocytes. Dexamethasone (DEX) and methylisobutylxanthine (MIX) are identified as direct inducers of C/EBPδ and C/EBPβ gene expression, respectively. During the early phase of differentiation, high levels of C/EBPδ and C/EBPβ accumulate, followed by the activation of C/EBPα in the terminal phase. The study demonstrates that precocious expression of C/EBPδ or C/EBPβ accelerates adipogenesis, while preventing their expression blocks terminal differentiation. Retrovirus-mediated overexpression of C/EBPβ and C/EBPδ in NIH-3T3 cells results in their conversion into committed adipoblasts, capable of synchronous and uniform differentiation into fat-laden adipocytes. The findings suggest a hierarchical regulatory cascade involving C/EBP proteins in adipocyte differentiation, with C/EBPδ and C/EBPβ playing early catalytic roles and C/EBPα regulating the final stages.