SMAD4 and breast cancer: Some of the Luminal A-specific TF regulators include SMAD4, which was shown to induce apoptosis in ERα-positive breast cancer cells (Li et al. 2005); NKX2-1 (also known as TTF-1), which regulates genes in the thyroid, lungs, and diencephalon during embryogenesis and whose expression has been detected in a small proportion of breast carcinomas (Robens et al. 2010); and FOXA1, which has been studied within the ERα pathway in luminal breast cancers and found to correlate with patient survival (Badve et al. 2007).