The degrees of methylation of MS[3] gene regions detectable with MS[3] probe were found to be nearly the same in F9 genome and TDM[1] genome.Nuclear transcripts of MS[3] genes were detected not only in F[9] cells but also in TDM[1] cells.These results suggest that the failure of detection of MS[3] RNA in the cytoplasm of differentiated cells may be mainly due to the defect of splicing the nuclear transcripts of MS[3] genes or inability of transfer of the mature MS[3] RNA from nucleus to cytoplasm.