We employed histological and immunochemical assays to identify the morphological changes and a cDNA microarray to assess the gene expression profile in the three models of dilated cardiomyopathy utilized: ventricular muscle-specific erbB4 knockout (erbB4-KO), doxorubicin-treated wildtype (WTD), and erbB4-KO (erbB4-KOD). The gene discussed is ERBB4; the disease is dilated cardiomyopathy.