Differential expression of miRNA processing genes between ER+ and ER- breast cancer samples. (a) miRNA biogenesis and function pathway. Genes significantly up-regulated and down-regulated in ER- compared to ER+ samples are shown in yellow and cyan, respectively. A gene - for example, Drosha - is marked grey to denote that it shows no significant differential expression between ER- and ER+ samples. (b) Expression levels of Ago1, Ago2, Dicer, and TRBP in ER+ (red) and ER- (green) samples. The mean and the standard deviation of the expression levels for each gene are shown as a bar and vertical line, respectively. Data for a gene are not shown if it is missing from a dataset. The combined P-value for each gene is also shown.