Tumor angiogenesis is primarily driven by hypoxia-induced upregulation of VEGF. The transcription factor that directly activates VEGF gene expression under hypoxic conditions is:

• A NF-κB
• B STAT3
• C AP-1
• D HIF-1α (Hypoxia Inducible Factor-1α) ✓

Explanation

Under normoxia, HIF-1α is hydroxylated by prolyl hydroxylase, recognized by VHL, ubiquitinated, and degraded. Hypoxia inhibits prolyl hydroxylase, allowing HIF-1α to accumulate, translocate to the nucleus, and activate VEGF transcription. NF-κB mediates inflammatory and survival signalling; STAT3 is activated by cytokines; AP-1 responds to growth factors and stress.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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