The role of aromatase in promoting breast cancer is well defined; factors derived from malignant epithelial cells such as prostaglandin E2 as well as trans-acting transcription factors such as Liver Receptor Homologue (LRH-1/NR5A2), cAMP response element binding protein (CREB), Activating Transcription Factor 2 (ATF2/CREB2) and CCAAT/enhancer binding protein δ (C/EBPδ) increase aromatase levels within the epithelial cells and surrounding adipose stromal fibroblasts [9-11]. The gene discussed is CYP19A1; the disease is breast cancer.