Northern blot analysis

Northern blot analysis was performed as described previously 18 with minor modifications. Briefly, 20 μg of RNA was resolved by 1% denaturing agarose gel electrophoresis and transferred to Hybond‐N membrane (GE Healthcare) by capillary transfer, followed by UV cross‐linking. For Northern blots using digoxin‐labeled oligonucleotide probes, the prehybridization/hybridization buffer (Ambion) was used according to the manufacturer's instructions. After hybridization, blots were incubated with HRP‐conjugated anti‐digoxin antibody. Immunolabelling was developed with ECL Western Blotting Detection Reagent (GE Amersham). Visualized images were obtained using Image Quant LAS‐4000 mini (GE Fujifilm).