ALK and non-small cell lung carcinoma: There are 15 different EML4-ALK fusion transcript variants identified to date, not including the rearrangement between ALK and other genes like TGF (chromosome 3) or KIF5B (chromosome 10), which both were identified as ALK-fusion partners from NSCLC specimens and are estimated to make up to 20% of the positive cases.2 The known variants 1, 2, 3a, 3b, 4, “4”, 5a, 5b, “5”, 6, 7, 8a, 8b, E17; ins68A20 and E20; ins18A20 include exon 2, 6, 13, 14, 15, 16, 17 and 20 of EML4 and exon 20 of ALK (5, 6).