Northern hybridization of t(12;15) leukemic cells.ETV6 full-length cDNA detects 6.2-, 4.3-, and 2.4-kb transcripts (solid arrowhead) in the t(12;15) leukemic cells and Kasumi-1, HL60, and K562 leukemic cell lines (left panel). TRKCprobe spanning the breakpoint detects a wild-type 14-kb transcript (solid arrowhead) in the NBTM cell line, whereas a 4.3-kb abnormal band (open arrowhead) is detected in the t(12;15) leukemic cells (right panel). No band is detected in HL60 or K562.