In the human breast cancer cell lines MCF-7, MDA-MB-231, BT-549, MDA-MB-453, SK-BR-3, and 4T1, miR-33b acts as a tumor suppressor to inhibit CSC properties, such as tumorsphere formation, the expression of stem markers, and self-renewal ability, by inhibiting the high-mobility group AT-hook 2 (HMGA2), spalt-like transcription factor 4 (SALL4), and twist family bHLH transcription factor 1 (Twist1). The gene discussed is TWIST1; the disease is neoplasm.