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: Pharmacology
The drug imatinib acts by inhibtion of- 
Select and explain. 
A. The drug imatinib acts by inhibtion of-, B. Glutathione reductase, C. Thymidile synthetase, D. Protein kinase
A: The drug imatinib acts by inhibtion of-
Answer: A: The drug imatinib acts by inhibtion of- 
Explanation: Ans. is 'a' i.e. Tyrosine kinase Imatinib inhibits tyrosine protein kinase in CML and the ones that are activated by platelet derived growth factor (PDGF) receptor, stem cell receptor and C-KIT receptor found in gastrointestinal stromal tumour (GIST).