1. Biochemists have discovered a protein kinase enzyme named BRAF that is an important link in a molecular pathway that causes a cell to divide. Normally. BRAF responds to signals
coming from outside the cell—signals calling for the cell to divide normally under normal
conditions. But there is a mutation in BRAF enzymes that causes it to activate the cell toward
division continually. In this way it gives rise to melanomas and thyroid or ovarian cancers.
Biochemists have also found a drug, vemurafenib, which binds selectively to mutant BRAF
totally inactivating it. Cells that have inactivated BRAF undergo apoptosis—a process that
leads to cell death.