Which oncogene product functions as a constitutively active GTPase due to a point mutation that impairs its intrinsic GTPase activity, locking it in the active GTP-bound state?
- A MYC
- B BCL2
- C RAS ✓
- D ERBB2 (HER2)
Correct answer: C. RAS
Explanation
RAS point mutations (most commonly at codons 12, 13, or 61) abolish intrinsic GTPase activity, preventing hydrolysis of GTP to GDP, so RAS remains permanently active and continuously stimulates downstream MAPK and PI3K pathways. MYC is a transcription factor amplified or translocated in many cancers. BCL2 is an anti-apoptotic protein overexpressed by translocation. HER2 is a receptor tyrosine kinase amplified in breast cancer.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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