In an attempt to interpret the different biological responses of breast cancer cells to TGF-β treatment, the mRNA expression levels of the TBRII and five previously recognized TGF-β response genes identified in our initial expression profiling experiments (Additional file 1), along with the well-characterized TGF-β inducible gene PAI-1 [51-53], were evaluated by Northern blotting (Fig. 2). This evidence concerns the gene SERPINE1 and breast cancer.