BMP-4 enhanced Notch signaling via Smad4 in MCF-10A cells, but it is still unclear how BMP-4 activates Notch signaling in breast cancer cells or how the intrinsic Notch signal-dependent EMT enhances the cancer stem cell properties of breast cancer cells (or induces the evolution/formation of cancer stem cells). The gene discussed is SMAD4; the disease is cancer.