The RB1 tumor suppressor gene product pRb normally restrains the cell cycle by binding and inhibiting which transcription factor?

• A p53
• B E2F ✓
• C c-Myc
• D NF-κB

Explanation

Hypophosphorylated pRb sequesters E2F transcription factors, preventing transcription of S-phase genes and blocking G1-to-S transition. Cyclin D/CDK4/6 phosphorylates pRb, releasing E2F and allowing cell cycle progression. Loss-of-function mutations in RB1 liberate E2F constitutively, driving uncontrolled proliferation seen in retinoblastoma and osteosarcoma.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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