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C/EBP is a sequence-specific DNA-binding protein.In order to identify its distribu-tion

localization and function

immunocytochemical technique（ABC method）was done usinganti-C/EBP polypeptide antibodies 1103

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in liver specimens from 20 normal adult

5neonatal

6 patients with hepatitis

25 patients with liver cirrhosis

80 patients with hepatocellu-lar carcinoma（40 cases were associated with surrounding nontumorous tissues）and 26 patientswith cholangiocarcinoma（15 cases were associated with surrounding nontumorous tissues）.Theresults showed that C/EBP was diffusely distributed in nuclei and cytoplasm of differentiated liv-er cells and very low or undetectable in liver cancer cells.The expression of C/EBP was in pro-portion to differentiated degree of tumor cells

and was obviously weaker than that in surround-ing nontumorous tissues.C/EBP positive staining has also been found in regenerating epithelialcells of bile ductules.The results suggested that C/EBP might play an important role in estab-lishing and maintaining the differentiation of liver cells and might exert an inhibiting effect againsttransformation of liver cells and proliferation of neoplastic tissue.