<prompt> Which of the following anti-cancer drug is NOT s-phase specific:MethotrexateMercaptopurineIfosfamideThioguanine  <response>: Cytotoxic drugs are either cell cycle specific CCS or cell cycle nonspecific CCNS. a Cell cycle nonspecific Kill resting as well as dividing cells, e.g. nitrogen mustard, cyclophosphamide, chlorambucil, carmustine, dacarbazine, busulfan, L-asparaginase, cisplatin, procarbazine, actinomycin D. b Cell cycle specific Kill only actively dividing cells. Their toxicity is generally expressed in S phase. However, these drugs may show considerable phase selectivity, e.g.- G1: Vinblastine. S : Mtx, cytarabine, 6-TG, 6-MP, 5-FU, hydroxyurea, mitomycin C, doxorubicin, daunorubicin. G2: Daunorubicin, bleomycin, etoposide, topotecan. M: Vincristine, vinblastine, paclitaxel, docetaxel ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:830 