For example, constitutive activation of signal transducer and activator of transcription 3 (STAT3) promotes breast cancer progression through regulating Bcl‐2, Bax, VEGF and MMP‐7.28 Meanwhile, STAT3 acts synergistically with myocardin to regulate Bcl‐2 and Bax in cardiomyocytes, consequently inhibiting cardiomyocyte apoptosis via the mitochondrial apoptotic pathway.29 Hence, efforts to target STAT3 in breast cancer had little success in the past because of the potential adverse effects, such as cardiotoxicity. Here, STAT3 is linked to breast cancer.