RSIS is now found. The expression of a target gene can be inhibited by inserting RSIS to any boundary among a promoter sequence derived from the target gene, a 5'-terminal sequence of mRNA for the target gene and a terminator sequence for the target gene following the termination codon and including 3'-UTR. It is also found that the expression of two different genes can be inhibited simultaneously in a cell in which promoters derived from the genes can act, by using the promoters and the terminators derived from the genes and parts of mRNA molecules for the genes.
