Consistent with the in vitro results, miR-27a negatively regulated the suppressive function of TMEM170B (62% vs. 45% for MCF7 xenografts, P < 0.01; 62% vs. 41% for MDA-MB-231 xenografts, P < 0.01, Fig. 3e–h), indicating that the miR-27a/TMEM170B axis may be a critical factor that drives tumorigenesis in breast cancer. The gene discussed is TMEM170B; the disease is breast cancer.