PTEN and breast cancer: Immunohistochemical analysis indicated that PTEN and BRCA1 are downregulated in 47% and 77.8% of metastatic breast cancer tissues, respectively (Fig. S5 and S6), and the levels of PTEN and BRCA1 were both negatively correlated with the miR-20b expression (Fig. 6D) (r=−0.996 and −0.778, respectively).