PTEN and breast cancer: PTEN is a negative regulator of the PI3K/AKT signal pathway, and it critically determines ischaemic cardiomyocyte apoptosis, left ventricular remodelling caused by myocardial infarction, ischaemia reperfusion injury and cardiac contractile dysfunction.16, 17, 18, 19 It has been demonstrated that PTEN inhibits CH by modulating actin dynamics.20 On the other hand, miR‐20b has been reported to directly regulate PTEN expression in breast cancer cells.21