Immunohistochemical detection of EML4-ALK has proved difficult, however, likely as a result of low transcriptional activity conferred by the promoter-enhancer region of EML4.     ///    Our iAEP method discriminated between tumors positive or negative for EML4-ALK in a test set of specimens.     ///    The sensitivity of EML4-ALK detection by immunohistochemistry should be increased adequately.     ///    "These 8 tumors were found to include 1 with EML4-ALK variant 1, 1 with variant 2, 3 with variant 3, and 2 with previously unidentified variants (designated variants 6 and 7). "    ///    " EML4-ALK is a transforming fusion tyrosine kinase, several isoforms of which have been identified in lung cancer. "