Which of the following is a tumour suppressor gene whose protein product regulates the G1/S checkpoint by binding E2F transcription factors?
- A RAS
- B MYC
- C RB1 ✓
- D BCR-ABL
Correct answer: C. RB1
Explanation
The RB1 gene product sequesters E2F in its hypophosphorylated state, arresting cells at the restriction point before S phase; phosphorylation by cyclin D-CDK4/6 releases E2F and permits progression. Loss of RB1 causes retinoblastoma and osteosarcoma. RAS, MYC and BCR-ABL are proto-oncogene or fusion oncoproteins that drive proliferation, so they cannot be the answer for a checkpoint-regulating tumour suppressor.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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