This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
In apoptosis, cytochrome C acts through - 
Select and explain. 
A. Apaf 1, B. Bcl-2, C. FADD, D. TNF
A: Apaf 1
Answer: A: Apaf 1 
Explanation: Ans. is 'a' i.e., Apaf 1o One of these proteins is cytochrome c, well known for its role in mitochondrial respiration. In the cytosol, cytochrome C binds to a protein called Apaf-1 (apoptosis activating factor-1), and the complex activates caspase-9. (Bc1-2 and Bcl-x may also directly inhibit Apaf-1 activation, and their loss from cells may permit activation of Apaf-1).