This study was aimed at identifying novel NPM/ALK-binding proteins that might contribute to its oncogenic transformation.     ///    Protein-protein interactions involving NPM/ALK are important for the activation of downstream signaling pathways.     ///    The interaction between NPM/ALK and PSF was dependent on an active ALK kinase domain and PSF was found to be tyrosine-phosphorylated in NPM/ALK-expressing cell lines and in primary ALK(+) ALCL samples.     ///    "Using a proteomic approach, several RNA/DNA-binding proteins were found to coimmunoprecipitate with NPM/ALK, including the multifunctional polypyrimidine tract binding proteinassociated splicing factor (PSF). "    ///    Y293F PSF was not phosphorylated by NPM/ALK and was not delocalized in NPM/ALK(+) cells.     ///    NPM/ALK binds and phosphorylates the RNA/DNA-binding protein PSF in anaplastic large-cell lymphoma..     ///    "These results identify PSF as a novel NPM/ALK-binding protein and substrate, and suggest that PSF function may be perturbed in NPM/ALK-transformed cells.. "    ///    The expression of ALK fusion proteins induced delocalization of PSF from the nucleus to the cytoplasm and forced overexpression of PSF-inhibited proliferation and induced apoptosis in cells expressing NPM/ALK. 