Selectivity of MEC capture assessed by real-time quantitative PCR. To estimate contamination of the laser-captured MEC by adjacent MMC as well as by immune cells (macrophages and lymphocytes) mRNA transcript levels of cell-specific markers were assessed by measuring the relative expression of the relevant genes between captured cells and mammary tissue scrapes, i.e. the mammary tissue remaining on slides, after LCM. Relative quantities of specific markers from MMC (Krt14), macrophages (CD68), lymphocytes (CD3e) and MEC (CSN1S2, LALBA) were assessed after normalization (PPAI and/or RPS24). FASN, a gene expressed in a large panel of cell types, including adipocytes and MEC, was also assessed in the same conditions. Mean RQ values are given for each gene. Krt14 decreased (RQ = 0.14; ca. 7-folds reduction) in the captured cells compared with the whole mammary tissue. Likewise the same ratio was observed with CD68 (RQ mean = 0.18) and CD3e (RQ mean = 0.14). Levels of LALBA (RQ mean = 1.47 fold), CSN1S2 (RQ mean = 1.33 fold) were significantly increased. *indicates ratio significantly different between cap and scraped tissue (p < 0.001).