The knockout mouse for caspase-9 has numerous defects but dies as a result of an enlarged brain. Caspase-9 is a critical regulator in the signal…

The knockout mouse for caspase-9 has numerous defects but dies as a result of an enlarged brain. Caspase-9 is a critical regulator in the signal transduction pathway in apoptosis. Why would the knockout mouse for caspase-9 exhibit this phenotype and die?