CyA induces apoptosis in ALL cells. The T-lineage ALL cell line CEM-C7 and the B-lineage ALL cell lines OP-1 (carrying the Philadelphia chromosome) and RS4;11 (with MLL gene rearrangements) were incubated with CyA (10 μmol/L) or the vehicle (ethanol 0.1%) for 48 hours. (A) Flow-cytometric dot plots illustrate changes in cell light-scatter properties typical of apoptosis caused by exposure to CyA. These consisted of decreased cell size (forward scatter, FSC; x-axis) and increased cell granularity (side scatter, SSC; y-axis). (B) Isometric contour plots illustrate binding of Annexin-V to phosphatidyl serine residues on the cell membrane (a feature of apoptosis) and propidium iodide labeling due to cell membrane permeabilization caused by CyA. (C) In all 3 cell lines, CyA induced a DNA ladder of a multiple of 180 base pairs, characteristic of apoptosis. Molecular mass markers are indicated.