Effects of pre-miRNA and intron on RFP expression. (A) Representative photographs of cells that were transfected with various RFP-expressing constructs 48 hours before photographing. a, c and e were transfected with pCAG-RFP-miR constructs. b, d, f were transfected with pCAG-RFP-miRint constructs. g was transfected with pCAG-RFP, which does not contain a pre-miRNA. h was transfected with pCAG-RFPint, which has an intron but no pre-miRNA. (B) Quantification of RFP levels from the experiment represented in (A). (C) Northern blot detecting RFP mRNA synthesized by various pCAG-RFP constructs. The table on the top shows whether the construct contains miRNA or/and intron. The numbers in the bottom indicate the relative levels of mRNA (the thick band) that are normalized to lane 2, which is set at 10. Six μg of total RNA was loaded for each lane.