PSF is delocalized to the cytoplasm in cells expressing ALK fusion proteins. Indirect immunofluorescence was performed on 293T cells transiently transfected with HA-PSF alone, or together with kinase-dead NPM/ALK (KD-N/A), NPM/ALK (N/A), GCN4/ALK (G/A), or with mutant HA-PSF-Y293F together with NPM/ALK (N/A). Fluorescence was detected by confocal microscopy. Nuclei were detected using propidium iodide (PI) shown in red (column 1). HA-PSF was detected by FITC staining shown in green (column 2). NPM/ALK was detected by Cy5 staining shown in blue (column 3). A transmission image in place of Cy5 staining is shown for cells transfected with HA-PSF alone. Images were acquired using a Nikon 60×/1.4 NA oil-immersion objective lens, a medium solution of 95% glycerol in PBS, and a Biorad Laser Sharp 2000 camera; image processing was done with Adobe Photoshop CS2 version 9.0.