One оf yоur cоlleаgues shows you these imаges of cross-sections from control (A) аnd mutant (B) E10.5 mouse embryos with a dotted line surrounding the DRG. The sections were incubated with a probe that labels activated Caspases (the dark product). Deletion of which gene would most likely result in the relative increase in caspase activation seen in the mutant DRG in B?