Oligoribonucleotides were synthesized on an Applied Biosystems DNA/RNA synthesizer, using b-cyanoethyl phosphoramidite chemistry (62) . For synthesis of standard RNA oligonucleotides, the commercially available phosphoramidites with 2 0 -O-tertbutyldimethylsilyl groups were used (Glen Research). For synthesis of 2 0 -O-methyl RNA oligonucleotides, the 3 0 -O-phosphoramidites of 2 0 -Omethylnucleotides were used (Glen Research and Proligo). The 3 0 -O-phosphoramidites of LNA nucleotides were synthesized according to the published procedures with some minor modifications (44, 47, 63) . The details of deprotection and purification of oligoribonucleotides were described previously (64) .