We apprehended that the discrepancy of results generated by the two groups (Kashiwagi et al., 2003; Kayashima et al., 2003) regarding the imprinting analysis of Atp10a/Atp10c in normal adult mice can be caused by the differences of mouse strain, age, brain region, the primers used for cDNA synthesis (random 6mer or oligo dT) and the primers used for RT-PCR. However, in this report, the only condition that is different applied by the two groups for this imprinting analysis is the use of different strains of mice. Thus, we agree that the most feasible explanation for the discrepancy is the strain background-dependent imprinting (as this report states). There are studies that can support this idea, such as the different imprinting status of mouse Kvlqt1 gene between strain backgrounds (Jiang et al. 1998) and the different phenotypes of the Ndn KO mice between strain backgrounds (Gerard et al., 1999; Tsai et al., 1999).