UNLABELLED: To clarify the involvement of the Stk11/Lkb1 gene in the development of hepatocellular carcinomas (HCCs), its alteration in rat HCCs induced by exogenous and endogenous liver carcinogenesis models was investigated. MATERIALS AND METHODS: Fifteen HCCs induced by N-nitrosodiethylamine (DEN) and 12 HCCs induced by a choline-deficient L-amino acid-defined (CDAA) diet were obtained. To assess mutations and aberrant transcriptions of the Stk11 gene, polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) and reverse transcription (RT)-PCR analyses were performed, respectively. RESULTS: A mutation was detected in only 1 out of 15 HCCs by DEN, but no mutations in 12 HCCs by the CDAA diet. Aberrant transcripts were found in 4 out of 15 HCCs by DEN and in 3 out of 12 HCCs by the CDAA diet. CONCLUSION: These results suggest that alterations of the Stk11 gene may play a limited role in both exogenous and endogenous rat liver carcinogenesis.