The assay also detected EML4-ALK variants 1 or 3 in three FFPE samples of surgically resected NSCLC shown to be positive for anaplastic lymphoma kinase rearrangement by fluorescence in situ hybridization.     ///    "We developed an assay system for the detection of EML4-ALK variants 1, 2, 3a, 3b, 4, 5a, 5b, 6, or 7 transcripts in total RNA obtained from formalin-fixed, paraffin-embedded (FFPE) specimens of NSCLC tissue. "    ///    "However, the currently available assays for the detection of the different variants of EML4-ALK have limitations. "    ///    Evaluation of the analytic sensitivity of the assay with serial dilutions of plasmids containing EML4-ALK complementary DNA sequences revealed it to be capable of the reliable detection of one copy of each plasmid per reaction.     ///    "Furthermore, the assay identified variant 1 of EML4-ALK in 3 of 20 FFPE biopsy samples from patients with advanced NSCLC. "    ///    Our novel assay is highly sensitive and effective for the detection of EML4-ALK in FFPE specimens..     ///    The assay is based on region-specific polymerase chain reaction amplification of EML4-ALK complementary DNA followed by specific single-base primer extension and analysis of the extension products by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. 