Promoter hypermethylation of RASSF1A gene in a non-small cell lung carcinoma silences a tumor suppressor that normally inhibits which oncogenic pathway?
- A PI3K-AKT-mTOR signaling
- B Ras-RAF-MAPK signaling ✓
- C Notch-Hes1 signaling
- D Hedgehog-Gli signaling
Correct answer: B. Ras-RAF-MAPK signaling
Explanation
RASSF1A (Ras association domain family 1A) is a Ras effector protein that sequesters active Ras and prevents downstream RAF-MAPK activation; its promoter hypermethylation is one of the most frequent epigenetic silencing events in lung, breast, and other carcinomas. Loss of RASSF1A allows unopposed Ras-RAF-MEK-ERK signaling, promoting proliferation and survival. RASSF1A also interacts with microtubules and promotes apoptosis through MST1/2 kinases.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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