BTG1 (B-cell Translocation Gene 1 ),a member of the BTG/TOB (Transducer of ErbB-2 )family of anti-proliferation factors,has been proven to have an unfavorable effect on muscle fiber growth in several species.The porcine BTG1 gene was cloned and its 5 flanking promoter region sequence,and characterized the expression patterns in different tissues of adult pigs and in fetal skeletal muscle at different developmental stages in two breeds.The tissue distribution pattern analyses revealed that the mRNA of porcine BTG1 was ubiquitously expressed in the six tissues of both Landrace and Tongcheng pigs.Realtime quantitatve reverse transcriptase-PCR results showed that BTG1 mRNA expression levels were significantly different among the three fetal ages in Tongcheng pigs,while no significant differences were found among the three ages in Landrace pigs.Furthermore,the expression of BTG1 in Landrace pigs was significantly lower than in Tongcheng pigs at all three ages.The temporal expression profiles of the BTG1 gene in mouse myoblast C2C12 cells were shown to be consistent with those of the myogenin gene.A single nucleotide polymorphism (SNP),g.281C ＞ T,was identified in the 3UTR and allele frequencies were detected in seven pig breed populations.Significant associations were found between the g.281C ＞ T polymorphism and growth and meat quality traits.Our results indicate that the porcine BTG1 gene could play a potential role in marker-assisted selection and as such may be a gene of economic importance.