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. Author manuscript; available in PMC: 2010 Apr 7.
Published in final edited form as: Dev Cell. 2009 Jan;16(1):21–34. doi: 10.1016/j.devcel.2008.12.012

Figure 1. The canonical apoptotic pathway is well conserved in C. elegans, Drosophila, and mammals.

Figure 1

Functional orthologs are color-coded. In C. elegans inhibition of the anti-apoptotic Bcl-2 family member, CED-9, by the pro-apoptotic BH3-only protein, EGL-1, releases CED-4 to promote activation of the caspase, CED-3. In Drosophila, the pro-apoptotic multi-domain Bcl-2 family members, Debcl and Buffy, promote Dark-mediated activation of Dronc followed by induction of the caspase cascade. Similarly, mammalian pro-apoptotic BH3-only proteins inhibit the anti-apoptotic Bcl-2 family members, Bcl-2 and Bcl-xL, to promote oligomerization of the multi-domain Bcl-2 family members, Bax and Bak. Adaptor proteins, such as Apaf-1, promote caspase activation, leading to apoptotic cell death. Note that in mammals, the caspase family has expanded substantially (see text). Bcl, B-cell lymphoma; CED, cell death abnormal; BH3, Bcl-2 homology 3; EGL, egg-laying defective; Dark, Drosophila Apaf-1 related killer.