Members of the SIX family are expressed at the low level in normal adult tissues but increased in human cancers.[47,48] We found that mRNA levels of SIX1, SIX2, SIX3, and SIX4 were higher in breast cancer as compared to normal counterparts, suggesting their overexpression may contribute to the development of breast cancer. The gene discussed is SIX4; the disease is breast carcinoma.