Effects of oligonucleotides on morphologic changes on induced differentiation of wild-type U-937 cells. Cells at an initial concentration of 0.2 × 106 cells/mL were preincubated for 24 hours with oligonucleotides at a concentration of 50 μmol/L. Cells were then induced with ATRA at 1 μmol/L. After 4 days of induction in the continuous presence of antisense Rb oligonucleotides or oligo buffer, cytospin slides were prepared and stained with May-Grünwald-Giemsa. Simultaneously, noninduced cells were incubated with antisense Rb oligonucleotides or oligo buffer and used as controls. Morphology was investigated by light microscopy. Cells incubated with oligo buffer only (A); with ATRA and oligo buffer (B); with antisense Rb oligonucleotides only (C); or with ATRA and antisense Rb oligonucleotides (D).
