However, as shown in Fig. 3C and 3D, estradiol (10 nM) treatment for 48hours did not significantly increase the survivin expression either in NS siRNA treated MDA-MB-468 cells or in NgBR knockdown MDA-MB-468 cells (NS: 1.054±0.008 vs siNgBR: 1.103±0.021, n = 3, p = 0.092). To further determine the potential roles of NgBR in regulating survivin expression and breast tumor cell growth, we knocked down NgBR in MCF-7 cells, which are a typical ER alpha positive breast carcinoma cell line, and examined the survivin expression and cell growth in response to estradiol treatment. This evidence concerns the gene ESR1 and breast carcinoma.