CCAAT/enhancer-binding proteins (C/EBPs) are a family of transcription factors with a conserved basic-leucine zipper (bZIP) domain at the C-terminus, involved in dimerization and DNA binding. Six members (C/EBPα–C/EBPζ) have been identified, with variations in size due to differential translation initiation sites and protein-protein interactions. C/EBPs regulate cellular proliferation, differentiation, metabolism, and inflammation, particularly in hepatocytes, adipocytes, and hematopoietic cells. Their expression is controlled by hormones, mitogens, cytokines, nutrients, and toxins, with complex regulation involving multiple levels. The C/EBP family has a conserved bZIP domain, enabling heterodimerization and interaction with specific DNA sequences. C/EBPα, -β, -δ, and -γ are intronless, while ε and ζ have multiple exons. The optimal C/EBP binding site is a dyad symmetrical repeat RTTGCGYAAY. C/EBP isoforms share high sequence identity in the C-terminal bZIP domain, which includes a DNA-binding region and a leucine zipper for dimerization. The basic region determines DNA binding specificity, with changes in spacing affecting binding activity. C/EBP proteins have diverse N-terminal regions, with some containing activation domains or negative regulatory regions. Different C/EBP isoforms can produce multiple polypeptides through alternative splicing or proteolysis. For example, C/EBPα produces 42 kDa and 30 kDa isoforms, while C/EBPβ produces 38 kDa (LAP*), 35 kDa (LAP), and 20 kDa (LIP) isoforms. LAP contains both activation and bZIP domains, while LIP lacks the activation domain and acts as a dominant-negative inhibitor. C/EBP family members are expressed in various tissues, with C/EBPα highly expressed in adipose tissue, liver, intestine, lung, adrenal gland, and placenta. C/EBPβ is expressed in liver, intestine, lung, adipose tissue, spleen, kidney, and myelomonocytic cells. C/EBPγ and ζ are ubiquitously expressed, while C/EBPε is restricted to myeloid and lymphoid cells. Expression is regulated by extracellular mediators during physiological and pathophysiological changes. The C/EBP family plays critical roles in cellular differentiation, particularly in adipocytes and myeloid cells. C/EBPα is essential for adipogenesis, with its expression regulated by adipogenic hormones. C/EBPα-deficient mice show reduced lipid accumulation, while C/EBPβ and δ are involved in myeloid differentiation. C/EBPα-deficient mice fail to undergo myCCAAT/enhancer-binding proteins (C/EBPs) are a family of transcription factors with a conserved basic-leucine zipper (bZIP) domain at the C-terminus, involved in dimerization and DNA binding. Six members (C/EBPα–C/EBPζ) have been identified, with variations in size due to differential translation initiation sites and protein-protein interactions. C/EBPs regulate cellular proliferation, differentiation, metabolism, and inflammation, particularly in hepatocytes, adipocytes, and hematopoietic cells. Their expression is controlled by hormones, mitogens, cytokines, nutrients, and toxins, with complex regulation involving multiple levels. The C/EBP family has a conserved bZIP domain, enabling heterodimerization and interaction with specific DNA sequences. C/EBPα, -β, -δ, and -γ are intronless, while ε and ζ have multiple exons. The optimal C/EBP binding site is a dyad symmetrical repeat RTTGCGYAAY. C/EBP isoforms share high sequence identity in the C-terminal bZIP domain, which includes a DNA-binding region and a leucine zipper for dimerization. The basic region determines DNA binding specificity, with changes in spacing affecting binding activity. C/EBP proteins have diverse N-terminal regions, with some containing activation domains or negative regulatory regions. Different C/EBP isoforms can produce multiple polypeptides through alternative splicing or proteolysis. For example, C/EBPα produces 42 kDa and 30 kDa isoforms, while C/EBPβ produces 38 kDa (LAP*), 35 kDa (LAP), and 20 kDa (LIP) isoforms. LAP contains both activation and bZIP domains, while LIP lacks the activation domain and acts as a dominant-negative inhibitor. C/EBP family members are expressed in various tissues, with C/EBPα highly expressed in adipose tissue, liver, intestine, lung, adrenal gland, and placenta. C/EBPβ is expressed in liver, intestine, lung, adipose tissue, spleen, kidney, and myelomonocytic cells. C/EBPγ and ζ are ubiquitously expressed, while C/EBPε is restricted to myeloid and lymphoid cells. Expression is regulated by extracellular mediators during physiological and pathophysiological changes. The C/EBP family plays critical roles in cellular differentiation, particularly in adipocytes and myeloid cells. C/EBPα is essential for adipogenesis, with its expression regulated by adipogenic hormones. C/EBPα-deficient mice show reduced lipid accumulation, while C/EBPβ and δ are involved in myeloid differentiation. C/EBPα-deficient mice fail to undergo my