This TGFβ2/Smad‐Snail1/EZH2‐miRNAsTGFβ2 feedforward circuitry is only operated in TNBC, not in luminal subtype BC because ERα interrupts this circuitry by interacting with Smad and blocking Snail1 expression in luminal BC. The gene discussed is TGFB2; the disease is breast cancer.