Total RNA from transiently transfected 293FT cells was extracted with RNA STAT-60 (Tel-Test, Friendswood, TX, USA) and separated on a 7.5% urea polyacrylamide gel. The transfer of RNA onto nitrocellulose membrane and hybridization were performed according to standard molecular biology protocols. The probe for detecting the expression of sh-B971 and its variants was a synthetic DNA oligomer corresponding to the bottom strand of sh-B971. Radioactive labeling of the probe was performed with an end-labeling protocol with T7 polynucleotide kinase (Ambion, Austin, TX, USA). The exposure and detection of the radioactive signal was performed with a Typhoon Imager (GE Healthcare, Piscataway, NJ, USA) with Quantity One software (Bio-Rad, Hercules, CA, USA).