miR-31 and its host gene LOC554202 are downregulated in basal TNBC cell lines and highly expressed in luminal non-invasive BC cell lines. (A and B) Quantitative real-time RT-PCR of the mature miR-31 (A) and the pri-miR-31 (B) in non-malignant breast epithelial MCF10A, luminal MCF7, SKBr3 and T47D, and basal triple-negative MDA-MB-435S, MDA-MB-231 and BT549 BC cell lines. miR-16 and RNUB6 were used for normalization. (C) Semi-quantitative RT-PCR of the LOC554202 transcript in the same cell lines. GAPDH was used an internal control.