In vitro apoptogenic effects of various compounds and chemotherapeutic agents in NB4 and NB4.437r cells. NB4 (open circles) or NB4.437r (closed circles) cells (5 × 10⁵/mL) were treated for an optimal amount of time with the indicated compounds at the indicated concentrations. The number of apoptotic cells was determined after staining with DAPI. Results are the mean ± SD of 3 separate culture dishes. Cells were treated for these periods of time: CD437, 6 hours; CD2325, 21 hours; fenretinide, 24 hours; doxorubicin (Doxo), 13 hours; AraC, 24 hours; taxol, 24 hours; staurosporine, 8 hours; cisplatin, 24 hours; Arsenic, 24 hours.