Antisense technology was developed to inhibit gene expression by utilizing an oligonucleotide complementary to the mRNA which encodes the target gene. There are a few possible mechanisms for the inhibitory effects of antisense oligonucleotides. Among them, degradation of mRNA by RNase H is considered to be the major mechanism of action for antisense oligonucleotides. This technique was originally used to elucidate the function of a target gene, but may also have therapeutic applications, provided it is designed carefully and properly.