Multiple Choice
Which of the following is not a characteristic of tumor cells?
20. Cancer
Overview of Cancer
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Mutant forms of the ras protein found in tumors would cause which of the following?
A
Inhibition of DNA replication
B
Continuous stimulation of cell division
C
Suppression of oncogene expression
D
Increased apoptosis in cancer cells
Verified step by step guidance1
Understand the role of the Ras protein: Ras is a small GTPase that acts as a molecular switch in cell signaling pathways. It is involved in transmitting signals from growth factor receptors on the cell surface to the nucleus, promoting cell division and survival.
Recognize the impact of mutations in Ras: Mutant forms of Ras are often locked in an active GTP-bound state, meaning they continuously signal downstream pathways, even in the absence of growth factor stimulation.
Connect Ras mutations to cell division: The continuous activation of Ras leads to the persistent stimulation of pathways like the MAPK/ERK pathway, which promotes cell proliferation and survival, contributing to uncontrolled cell division in tumors.
Eliminate incorrect options: Mutant Ras does not inhibit DNA replication, suppress oncogene expression, or increase apoptosis. Instead, it enhances oncogenic signaling and reduces apoptosis, favoring tumor growth.
Conclude the correct answer: The continuous stimulation of cell division is the direct result of mutant Ras activity, as it drives unregulated cell proliferation, a hallmark of cancer.
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