In breast cancer samples, expression of aromatase is upregulated in breast tumor tissue compared to normal tissue [28], indicating a potential role of CYP19 in the development and progression of breast cancer, and microarray expression profiling and clustering analysis have demonstrated a significant positive correlation between aromatase and estrogen-related receptor α mRNA expression in isolated carcinoma cells [29]. The gene discussed is CYP19A1; the disease is breast neoplasm.