Experimental validation of differential IR. (A) Fluorescence-activated cell sorting profiles of unsorted and sorted murine erythroid marrow cells. Target antigens and fluorophores are indicated along axes. (B) Bar graph depicts quantitative reverse-transcription polymerase chain reaction of β-major (Hbb-b1) mRNA levels normalized to β-actin mRNA levels. (C) Genes and introns are indicated above, samples are indicated below, and the ratio of intron-exon signals (intron retained) to exon-exon signals (intron spliced out) are indicated to the left of each graph. Graphs depict mean and standard error of the mean of 4 to 6 biological replicates. Asterisks indicate significance (Wilcoxon rank-sum test, P < .05). Arrows indicate quantitative polymerase chain reaction primer locations.