Confocal laser scanning microscopy of NPM1 wt and mutant cells. Cells of the NPM1-wt cell line MV4-11 (A) or mononuclear cells from patient samples with mutations DD-3 (B), DD-4 (C), or DD-1 (D) were stained with a monoclonal antibody against NPM1, Cy-3 labeled with a secondary antibody, and analyzed using confocal laser scanning microscopy. Nuclei were stained with DAPI; original magnification, × 240.