Which of the following drugs is most likely to inhibit a cancer cell in S phase?Question 12Select one:DocetaxelDacarbazinePemetrexedEpirubicin

The drug most likely to inhibit a cancer cell in S phase is Pemetrexed.

Here's why:

1. The S phase is a part of the cell cycle where DNA synthesis or replication occurs.

2. Pemetrexed is a chemotherapy drug that works by disrupting the cell cycle. It specifically inhibits the formation of DNA and RNA, which are necessary for the growth and survival of both normal cells and cancer cells.

3. Pemetrexed does this by inhibiting several enzymes (including thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyltransferase) that are involved in the synthesis of DNA and RNA.

4. By inhibiting these enzymes, Pemetrexed prevents cancer cells from replicating their DNA during the S phase, which in turn prevents them from dividing and growing.

5. On the other hand, Docetaxel, Dacarbazine, and Epirubicin work in different ways and at different stages of the cell cycle. For example, Docetaxel works by disrupting the function of microtubules during cell division, while Dacarbazine is an alkylating agent that can work in all phases of the cell cycle, and Epirubicin is an anthracycline antibiotic that works by intercalating DNA, inhibiting topoisomerase II, and creating free radicals that damage DNA.

6. Therefore, among the options given, Pemetrexed is the drug most likely to inhibit a cancer cell in the S phase.