.Beta.-D-Arabinofuranosyl-6-mercaptopurine 6H-Purine-6-thione, 9-.beta.-D-arabinofuranosyl-1,9-dihydro- 6MP-Arabinoside 892-49-9 AIDS-160246 AIDS160246 ARA-6MP Ara-MP Arabinosyl-6-mercaptopurine NSC406021