Large-scale screening and molecular characterization of EML4-ALK fusion variants in archival non-small-cell lung cancer tumor specimens using quantitative reverse transcription polymerase chain reaction assays..     ///    "This panel of variant-specific, quantitative RT-PCR assays detects common EML4-ALK+ variants as well as ALK gene expression level in archival formalin-fixed paraffin-embedded NSCLC specimens."    ///    ALK expression level varied significantly among different EML4-ALK+ variants and individual tumors. 