TGFB2 and breast cancer: This TGFβ2/Smads‐Snail1/EZH2‐miRNATGFβ2 feed‐forward circuitry is only operated in TNBC, not in luminal subtype BC because ERα interrupts this circuitry by interacting with Smads and blocking Snail1 expression in luminal subtype BC.