Based on the findings that miR133a functionally regulates the expression of UCP-2 in muscle cells and macrophages [22,23] and the significances of UCP-2 in chemotherapy resistances of cancer cells, it is postulated that miR133a might play a role in the chemotherapy resistance of breast cancer cells by regulating the expression of UCP-2. The gene discussed is UCP2; the disease is breast carcinoma.