PTEN and breast cancer: In esophageal squamous cell carcinoma, miR‐196a can promote cell growth by inhibiting GAS5.27 Zhang's study has shown that GAS5 is negatively correlated with miR‐21 expression in breast cancer cells, and that miR‐21 could not only interact with tumor suppressor gene PTEN, but also has the function of targeting lncRNA GAS5.28