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Figure S3. Failure to thrive is accompanied by apoptosis secondary to impaired cardiac development. Although apoptosis is increased in knockout animals (most prominently at E10.5), it is not restricted to the cardiac ventricle (d vs. h). Immunostaining with anti-α-actinin antibody is used to label the cardiac ventricle (top, red). Apoptotic cells stained with fluorescein are present in both knockout and wild-type animals at comparable levels at E9.5 (e and f) and strongly increased in the E10.5 knockout, predominantly outside the heart around the abdominal cavity (h vs. g). The fluorescein channel alone is provided in a' through h' to emphasize the apoptotic cells. Bar, 100 µm.