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: Microbiology
Pertusis toxin acts by all of the following mechanisms except ? 
Select and explain. 
A. ADP ribosylation of proteins associated with receptors, B. Increase cyclic AMP, C. Increased calcium release from sarcoplasmic reticulum, D. Acts through G alpha subunit
C: Increased calcium release from sarcoplasmic reticulum
Answer: C: Increased calcium release from sarcoplasmic reticulum 
Explanation: None