The results showed that co-transfection of miR-20b mimics and pGL3-wt significantly decreased the luciferase activities in breast cancer cells (ZR-75-30 and MCF-7) but not that of the mutant reporter (Figure 2B), indicating that miR-20b binds directly to the 3′-UTR of PTEN. This evidence concerns the gene PTEN and breast cancer.