Furthermore, precise roles of Ras of D. melanogaster and other insects are expected to be considerably different, since the patterns of the development and body structures are highly diverse among insect species. Therefore, Ras studies using various insect species are thought to provide more beneficial information on the direct link between the hormonal regulation of insect growth and the function of Ras in the molecular interaction level. mRNA expression levels of three Bmras in various tissues of various developmental stages were measured using the CCT241533 qRT-PCR technique. In whole body samples, Bmras2 transcripts tended to be more abundant than Bmras1 and BmRas3 through the development. All ras transcripts were low level until the 4th instar, and gradually increased from day 6 of the 5th instar. They then showed a high expression in the pupal stage. However, when expression patterns of Bmras were compared precisely, there were differences among their expression patterns. Bmras1 and Bmras3 initially had an intensive expression, a moderate expression in the middle and a high expression again at the end of the pupal stage. In addition, they have small peaks of expression at the end of each larval stadium. Ras small GTPase is one of the most intensively studied molecules in signal transduction. However, its functions have not been investigated in insects except for D. melanogaster. Here, we try to clarify the function of Ras in B. mori, a model insect of endocrinological studies, to understand its roles in the hormonal regulation of insect development. From the sequence homology of Ras proteins, we cloned ras cDNAs from B. mori and determined their sequences. As in the case of D. melanogaster, three ras genes were identified. Phylogenetic analysis revealed that three Ras of B. mori corresponded to those of Drosophila. There were some differences in amino acid residues at effector interaction sites, GEF interaction sites and the C terminal CaaX motif among the Ilaprazole subfamily of Ras. Such differences classified three BmRas into separate subgroups. In phylogenetic analysis, only BmRas1 was grouped into the ��authentic�� Ras subfamily with DmRas1.