can't read?
6-mercaptopurine ( 6-MP ), is an analogue of the nucleobases adenine and guanine.
M 1645 (OTTO) 6-Mercaptopurine, 99% Cas 6112-76-1 - used antileukemic agent that inhibits de novo purine synthesis through incorporation of thiopurine methyltransferase metabolites into DNA and RNA.