Enzyme X and enzyme Y are involved in controlling cell division in lung cancer cells. Most lung cancer cells produce both enzyme X and enzyme Y. Some patients have a gene mutation that prevents their lung cancer cells from producing enzyme Y.
The pathway diagram below shows how cell division is regulated in these cancer cells:
Scientists have developed a drug that inhibits enzyme X. This drug specifically targets cancer cells.
a.[3]
Explain why this drug can be used to treat lung cancer in patients who have the gene mutation that stops their cancer cells from producing enzyme Y.
b.[2]
Explain why this drug would not be effective in treating lung cancer in patients who produce both enzyme X and enzyme Y.