BECAUSE of the importance of purine analogues in the chemotherapy of human neoplastic disease 1, several investigations have been made on their mode of action and the mechanism of resistance 2 to them ...
Tocchini-Valentini, G. P., Stodolsky, S., Sarnat, A., Graziosi, F., Weiss, S. B., and Guiduchek, E. P., Proc. U.S. Nat. Acad. Sci., 50, 935 (1963).