All of the following anticancer drugs act on G2 phase except:
## **Core Concept**
The cell cycle consists of several phases: G1, S, G2, and M. Anticancer drugs often target specific phases of the cell cycle to inhibit cancer cell proliferation. The G2 phase is a critical checkpoint before cell division, where DNA damage can be repaired or cells can undergo apoptosis if damage is irreparable.
## **Why the Correct Answer is Right**
acts on the G2 phase by inhibiting topoisomerase II, an enzyme critical for DNA replication and cell division. This action results in DNA damage and prevents cells from entering mitosis. On the other hand, primarily works by binding to microtubules of the mitotic spindle, preventing cell division (M phase).
## **Why Each Wrong Option is Incorrect**
* **Option A:** acts during the G2/M phase by interfering with microtubule function indirectly; it gets activated in the G2 phase to affect mitosis.
* **Option B:** works by inhibiting topoisomerase I, which is involved in DNA replication (S phase) but can have effects observed in the G2 phase due to the cell cycle's progression.
* **Option C:** primarily acts by intercalating DNA, thereby inhibiting topoisomerase II, similar to , affecting the G2 phase.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that anticancer drugs can have cell cycle-specific or -non-specific actions. Drugs targeting the G2 phase are particularly useful in treating rapidly dividing cancer cells.
## **Correct Answer:** . Paclitaxel