To explore the role of C14orf166 in the progression of breast cancer cells, we overexpressed C14or166 in breast cancer cells ZR-75-1 and MDA-MB361 to determine its effect on cell proliferation, MTT analysis found C14orf166 overexpression increased proliferation rate of breast cancer cells (Fig. 4a), colony formation assay suggested C14orf166 overexpression significantly promoted proliferation of breast cancer cells (Fig. 4b). This evidence concerns the gene RTRAF and breast carcinoma.