 Therefore, kinase inhibitors, such as imatinib, are often effective cancer treatments.Most tyrosine kinases have an associated protein tyrosine phosphatase, which removes the phosphate group.Protein kinases are a group of enzymes that possess a catalytic subunit that transfers the gamma (terminal) phosphate from nucleoside triphosphates (often ATP) to one or more amino acid residues in a protein substrate side-chain, resulting in a conformational change affecting protein function.