To further examined the effect of C14orff166 on cell proliferation, we downregulated C14orf166 used small inference RNA (siRNA), MTT analysis found knockdown of C14orf166 reduced proliferation rate of breast cancer cells (Fig. 4a), colony formation assay confirmed that C14orf166 knockdown significantly inhibited proliferation of breast cancer cells (Fig. 4b). This evidence concerns the gene RTRAF and breast cancer.