HMOX1 and cardiomyopathy: In addition, the myocardial antioxidation proteins (Nrf2, HO‐1, SOD1, SOD2), Sirt1 (a regulator of cellular ageing, apoptosis, stress, etc) and pAMPK (a regulator of cellular energy homeostasis) were down‐regulated in mouse hearts with doxorubicin cardiomyopathy (Figure 2).