3-Deazaneplanocin A (DZNep) hydrochloride is a potent histone methyltransferase EZH2 inhibitor. Treatment of OCI-AML3 cells with 3-Deazaneplanocin A (1.0 μM) results in a significant increase in accumulation of cells in the G0/G1 phase (58.5%) with a concomitant decrease in the number of cells in S phase (35.2%) and G2/M phases (6.3%) of the cell cycle (P<0.05). Treatment with 3-Deazaneplanocin A (200 nM to 2.0 μM) for 48 hours, dose dependently, inhibits colony growth of OCI-AML3 and HL-60 cells. 3-Deazaneplanocin A (DZNep) hydrochloride reduces the expression of EZH2, especially after 72 hours (e.g. 48%, 32% and 36% reduction of EZH2 in PANC-1, MIA-PaCa-2 and LPc006 cells, respectively). 3-Deazaneplanocin A (DZNep) hydrochloride shows minimal growth inhibition in PANC-1 cells. More than 50% of these cells are still growing after exposure at the highest concentration (20 μM). MIA-PaCa-2 and LPc006 cells are much more sensitive, with IC0 values of 1.0±0.3 and 0.10±0.03 μM, respectively. 3-Deazaneplanocin A (DZNep) hydrochloride causes dose-dependent inhibition of cell proliferation of NSCLC cell lines, and the IC0 values range from 0.08 to 0.24 μM.