Analysis of microRNA (miRNA) gene expression in breast cancer cell lines and normal tissue. (a) Global miRNA heatmap. Log2 ratios of spots with intensity (A values) greater than 6 were used in CIMminer clustering analysis using correlation distances. (b) Heatmap of differentially expressed miRNAs. miRNA genes for which at least one value differed with log2 greater than 2.5 from the pool (either upregulated or downregulated) were used in CIMminer clustering analysis using correlation distance (upper). The PN miRNA cluster is indicated by a star and is enlarged (lower). The cell type origin (B, basal; L, luminal; N, normal; S?, possible stem cell) and the status of oestrogen receptor/progesterone receptor (ER/PR) are indicated on the left. PN miRNA, microRNA specifically expressed in PMC42 and Normal breast tissue.