TGFB1 and breast cancer: Next, to investigate whether CAF‐increased TGF‐β signalling could enhance breast cancer cell aggressiveness, we established a model where Gaussia luciferase‐labelled MCF7 (MCF7.Gluc) breast cancer cells were co‐cultured with 19TT CAFs on top of transwell insert‐membranes (Figure 6a).