Which of the following anticancer agents acts specifically during the S phase of the cell cycle?

• A Bleomycin
• B Cyclophosphamide
• C Cytarabine ✓
• D L-asparaginase

Explanation

Cytarabine is an S-phase-specific antimetabolite that is phosphorylated intracellularly to ara-CTP and incorporated into DNA, where it inhibits DNA polymerase and terminates chain elongation. Cyclophosphamide is cell cycle nonspecific, acting at any point. Bleomycin acts mainly in G2 and M phases, while L-asparaginase arrests cells in G1 by depleting circulating asparagine.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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