This NPM-ALK FISH assay was initially validated by analysis of a series of cytogenetically characterized cell lines, with the presence of the der(5) chromosome showed specifically only in those lines known to contain the t(2;5).     ///    Detection of the t(2;5)(p23;q35) and NPM-ALK fusion in non-Hodgkin's lymphoma by two-color fluorescence in situ hybridization.. 