Consider the Ras Signal-Transduction Pathway

question 10

Multiple Choice

Consider the Ras signal-transduction pathway. Suppose a mutation occurred in the gene that encodes MEK that renders it nonfunctional. Which of the following effects would you see in this situation?

• A) Binding of the growth factor to the receptor would occur, but the receptor's conformational change that is needed for the pathway to go forward would not occur.
• B) Activated Ras would no longer have the ability to activate Raf, and the signal-transduction pathway would be halted at this step.
• C) Ras would lose the ability to bind GTP and thus could no longer become activated, and the signal-transduction pathway would be halted at this step.
• D) MAP kinase would not be activated and thus could not move into the nucleus to activate transcription factors.
• E) Inactive Ras would move into the nucleus and inactivate tumor-suppressor transcription factors, which could ultimately result in cancer.

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