FIG. 1. ErbB2 conditional knockout (CKO) mice display multiple features of dilated cardiomyopathy. (Top panel) The heart from erbB2 CKO mutants is enlarged due to dilated left ventricle (LV), as shown in hematoxylin/eosin (H/E)-stained cross-sections of the heart (middle panel). Echocardiography (bottom panel) and hemodynamic measurements demonstrate an enlarged LV with thin walls and decreased contractility. Electron microscopy reveals intact cytostructural architecture but increased mitochondria and vacuolar structures (similar to features observed following anthracycline toxicity). ErbB2 CKO cardiomyocytes are more susceptible to anthracyline toxicity in culture. [Reprinted from Crone SA, Zhao YY, Fan L, Gu Y, Minamisawa S, Liu Y, Peterson KL, Chen J, Kahn R, Condorelli G, Ross J Jr, Chien KR, Lee KF 2002 ErbB2 is essential in the prevention of dilated cardiomyopathy. Nature Med 8(5):459–465, with permission of the Nature Publishing Group.]