Fig. 3.

F- and Cl-amidine induce the differentiation of HL-60 cells. a HL-60 cells were exposed to ATRA, or F-, or Cl-amidine over the course of 48 h with samples taken after 6, 12, 24, and 48 h. ATRA served as the positive control. PBS was used as the vehicle control. Myeloperoxidase and PAD4 protein levels were determined by Western blotting. b Myeloperoxidase activity in HL-60 cells in response to incubation with ATRA, and F- and Cl-amidine after 24 and 48 h. Specific activity is defined as the rate of formation of 1 mol of tetraguaiacol from 1 mol guaiacol and 4 mol of H₂O₂. Significant decreases in myeloperoxidase activity, as compared to the PBS vehicle control, were observed after 48 h of incubation (*p < 0.05). c Relative PAD4 mRNA levels, as determined by quantitative RT-PCR, in response to treatment with ATRA, and F-, and Cl-amidine for 48 h