In conclusion, our data generated by analyzing human breast cancer microarray data, RT-PCR, and promoter driving luciferase reporters indicate that Grhl2 is specifically expressed in epithelial cells and tightly co-regulated with E-cadherin, suggesting that Grhl2 is the essential transcription factor that determines the epithelial phenotype of breast cancer cells. The gene discussed is GRHL2; the disease is breast carcinoma.