BAX and congestive heart failure: Compared with wild-type mice, mice with a loss-of-function mutation in TNF receptor superfamily member 6 had less apoptosis, as measured by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL).156 Genetic deletion of the proapoptotic factor Bax or overexpression of the antiapoptotic factor Bcl-2 limited myocardial infarction in an I/R model.157,158 Human chronic heart failure samples had more TUNEL-positive apoptotic cells than nonheart failure control samples.146 Collectively, these data suggested the involvement of apoptosis in the chronic heart failure.