Abstract:  Objective To analyze mutations in the protein-coding region of the POLD1 gene in the human hepatocarcinoma cell line SMMC-7721；this gene encodes an enzyme critical for DNA replication. Methods Total RNA was isolated from SMMC-7721 cultures，and the POLD1 gene coding region was amplified by RT-PCR，purified and A-tailed， and then cloned into a T-vector. Mutations were detected by sequencing. Results The protein-coding region of the POLD1 gene was successfully amplified and found to contain 12 mutations，11 of which were nucleotide changes and 1 was a nucleotide deletion. Conclusions SMMC-7721 en-codes a mutated POLD1 gene， and the mutations lead to changes in the protein sequence.

Key words:  Liver neoplasms, POLD1, Mutation