qPCR analysis of fibroblast populations confirmed that CAFs from more aggressive breast tumours have an ‘activated' CAF phenotype as evidenced by the gradient increase in expression of the myofibroblast markers αSMA (Acta2)2, transgelin (Tagln)18 and TGFβ1 (Tgfb1)19, 20, 21 from control mouse mammary gland fibroblasts (MGFs) to 4T07 fibroblasts to 410.4/4T1 fibroblasts (Fig. 1c). The gene discussed is TGFB1; the disease is breast neoplasm.