This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
Which protein is absent in saliva? 
Select and explain. 
A. Lactoferrin, B. Amylase, C. Mucin, D. Intrinsic factor
D: Intrinsic factor
Answer: D: Intrinsic factor 
Explanation: Intrinsic factor is secreted by the parietal cells of the stomach and is not secreted by the salivary glands. Lactoferrin, amylase, mucin, and muramidase are found in saliva.