This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
In the apoptosis,Apaf-1 is activated by release of which of the following substances from the mitochondria 
Select and explain. 
A. Bcl-2, B. Bax, C. Bcl-XL, D. Cytochrome c
D: Cytochrome c
Answer: D: Cytochrome c 
Explanation: Ref, Harrison 17/e p506,9/ep55 Apoptosis or programmed cell death can be induced by intrinsic or extrinsic pathway.as can be seen in the intrinsic pathway;cytc gets associatio with ApAF-1 which activates caspases and causes cell death