Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: When lactose is present, the repressor protein does not bind to the operator. This allows RNA polymerase to bind to the promoter and begin transcription. As a result, the lac genes are expressed, and lactose is digested. Answer: nonbinding of repressor protein
A:
When lactose is present in the cell, what allows the lac genes to be expressed?