Effects of oligonucleotides on ATRA or Vit D3-induced monocytic differentiation in wild-type U-937 cells assayed by the cells' capacity to reduce NBT. Cells at an initial concentration of 0.2 × 106 cells/mL were preincubated for 24 hours with phosphorothioate-modified oligonucleotides at a concentration of 50 μmol/L. Cells were then induced with ATRA or Vit D3 at 1 μmol/L and 0.1 μmol/L, respectively. After 4 days of induction in the continuous presence of (▪) antisense RB oligonucleotides, (▨) sense RB oligonucleotides, or (□) oligo buffer, respectively, cells were subjected to NBT reduction test. As controls, noninduced cells were incubated with antisense RB oligonucleotides, sense RB oligonucleotides, or oligo buffer, respectively. The percentage of NBT reducing cells was determined by counting 200 cells. Results are shown from one representative experiment.
