n. 1. an agent that can convert the inactive form of an enzyme (see proenzyme) to the active form. 2. an enzyme that catalyses the transfer of phosphate groups. An example is *phosphofructokinase.
an enzyme that catalyses the transfer of a phosphate group from ATP to a specific amino acid residue of an intracellular protein (usually serine, threonine, or tyrosine), thereby affecting the biological activity of the protein. Protein kinase inhibitors are drugs that block the action of protein kinases in tumour cells and are used in the treatment of cancer. They include *sorafenib, *sunitinib, and *temsirolimus. See also tyrosine kinase inhibitor.... protein kinase
any one of a class of drugs that interfere with cell growth in a variety of different ways by inhibiting the action of tyrosine kinases. This family of enzymes, which occur both within cells and as components of cell-membrane receptor sites, have an important role in cell division and cell growth. Many tumour cells have been shown to have both intracellular enzymes and extracellular receptor sites, and a variety of anticancer agents have been developed to inhibit enzyme activity at these sites. Among these drugs are *imatinib, dasatinib, and nilotinib, used for treating chronic myeloid leukaemia; *sunitinib, for treating renal cell carcinoma; and erlotinib, for treating pancreatic cancer and non-small-cell lung cancer. See also epidermal growth factor receptor.... tyrosine kinase inhibitor
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