Marbling defined by the amount and distribution of intramuscular fat, so-called Shimofuri is an economically important trait of beef cattle in Japan. Researchers have recently reported that a Single Nucleotide Polymorphism (SNP) referred to as rs41648172 in mtron 6 region of the Pancreatic Lipase (PNLIP) gens which have been considered as a positional functional candidate for the gene responsible for marbling was associated with marbling in Japanese Black beef cattle with the T allele being associated with a high level of marbling. In this study, researchers investigated the allele frequency distribution of the rs41648172 SNP among the 5 cattle breeds, Japanese Black, Japanese Brown, Japanese Short Horn, Holstein and Brown Swiss breeds. The T allele at the rs41648172 SNP associated with high marbling was found at higher frequency in Japanese Black breed that has been subjected to a strong selection for high marbling than in the other breeds that have not been strongly selected for high marbling. Based on this finding, researchers hypothesized that the pressure of the strong selection for high marbling in the Japanese Black breed has increased the frequency of the T allele at the rs41648172 SNP in the PNLIP. This study, together with the previous association study, suggested that the PNLIP SNP may be useful for effective marker-assisted selection to increase the levels of marbling. © Medwell Journals, 2012.