TGFB1 and breast carcinoma: Matrix stiffness regulated this effect by regulating the PI3K/Akt pathway rather than Smad to switch the effect of TGFβ, which induced breast cell apoptosis in the soft matrix but EMT in the stiff matrix.[9b] Breast cancer cells cultured on aligned fibers showed upregulated expression of metastasis‐related EMT genes, and elongated spindle‐like morphology rather than flat stellar shape in messy fibers.