5-azaC decreases intracellular deoxyribonucleotide pools. MV4-11 or K562 cells were treated with the indicated concentrations of 5-azaC for 72 hours and subjected to LC-MS/MS analysis for deoxyribonucleotide levels. 5-azaC dose-dependently reduces the dTTP, dATP, dCTP, and dGTP/ATP levels in MV4-11 (A) and K562 (B) cells. Data are presented as a percentage of the untreated controls. The results are means ± SD of a representative experiment performed in triplicate. *P < .05 and **P < .01 versus untreated controls.