Further studies demonstrated that although BAG5 homozygous knockout (BAG5−/−) mice did not spontaneously develop a DCM phenotype, under tunicamycin (TN)-induced ERS conditions, BAG5−/− mice showed a marked decrease in LVEF and left ventricular fractional shortening (LVFS) compared with BAG5+/− and BAG5+/+ mice. This evidence concerns the gene BAG5 and familial dilated cardiomyopathy.