Effect of lycorine on cytochrome c release. Cells were fixed and labelled for cytochrome c (red) and DNA (blue). (A) HL-60 cells in control group. (B) Cells were treated with 5.0 μM lycorine for 24 h. Cell nuclei were observed by DNA staining with DAPI (A2, B2). The staining pattern of cytochrome c became diffusive in most cells (B1), consistent with a translocation of cytochrome c into the cytosol and nucleus (B3), whereas cytochrome c displayed a dotted pattern in untreated cells, consistent with its location within mitochondria (A1, A3). Images were obtained with a confocal microscope (×400).