Imatinib used in CML acts by -

Ans. is 'c' i.e. Competitive inhibition of ATP binding site of ABL kinase o In CML, there is Bcr-Abl translocation which leads to unregulated activation of intracellular (non-receptor) tyrosine kinase, Le., Bcr-Abl tyrosine kinase. o Imatinib is a Bcr-Abl tyrosine kinase (intracellular-nonreceptor tyrosine kinase) inhibitor. o This drug block the activity of nonreceptor tyrosine kinase by acting as a inhibitor of the ATP binding site on the protein and prevents its phosphorylation. About option 'a' o Imatinib does not inhibit Bcr-Abl translocation, it inhibits overactive tyrosine kinase after Bcr-Abl translocation has already occured.