Schematic diagram showing the method for identifying RE-changing miRNAs between ER- and ER+ breast cancer samples. For each miRNA in each sample, a RE-score is calculated by comparing average ranks of its target and non-target genes. RE-changing miR (ER- > ER+) and RE-changing miR (ER- < ER+) represent miRNAs that have significantly higher and lower RE-scores in ER- compared to ER+ samples, respectively. RE-invariant miR represents miRNAs that show no significant difference in RE-scores between these samples. Note that many miRNAs share the same target mRNA, while many mRNAs can also be targeted by the same miRNA, which constitutes a complex miRNA-mRNA network.