Nested RT-PCR of fusion transcripts. Results indicate that ETV6 builds fusion transcripts with both the truncated and catalytically active NTRK3 (lane numbers explained below). ETV6-NTRK3 rearrangement: 1 control PCR of patient with ETV6-NTRK3-rearrangement (ABL1); 2 ETV6 exon5 and NTRK3 exon14; 3 ETV6 exon5 and NTRK3 exon14I; 4 ETV6 exon5 and NTRK3 exon14II; 5 ETV6 exon5 and NTRK3 exon17; all NTRK3 primers are specific for the tyrosine kinase domain. Controls: 6 control PCR of patient without ETV6-NTRK3-rearrangement (ABL1); 7 ETV6 exon5 and NTRK3 SequF (patient without ETV6-NTRK3-rearrangement); 10 water control. NTRK3-ETV6 Rearrangement: 8,9 NTRK3 exon12 (2 primers) and ETV6 exon6.