Altered expression of miR-21 in different breast tumor types and breast cell lines. (a) CISH detection using miR-21 LNA detection probe (blue) or scramble-miR as negative control were performed on consecutive 8 μM cryo-sections obtained from BC/FA tissues and corresponding NATs. DNA was counterstained with methyl green (green, × 400 magnification). (b) Total RNA was used to quantify miR-21 expression by relative qRT-PCR, normalizing on U6 RNA levels. The graph shows a log2-scale RQ calculated by normalizing the miR-21 expression values in the tumors on those in the NATs. Data indicate the mean (+SD) of four independent samples. * P < 0.05. (c) FISH detection of miR-21 in five BC cell lines (MCF-7, MDA-MB-231, MDA-MB-453, MDA-MB-435, SK-BR-3) and one non-tumorigenic epithelial cell line (MCF-10A). Positive in situ hybridization signals are visualized in green, while blue depicts DAPI nuclear stain (× 1,000 magnification). (d) qRT-PCR analysis show that MCF-7, MDA-MB-231 and MDA-MB-453 cells express higher levels of miR-21 compared with MCF-10A cells. Data are mean (+SD) of three replicates. ** P < 0.01; BC, breast cancer; FA, fibroadenoma; NATs, normal adjacent tissues.