RT-PCR detection of the TEL/AML1 fusion transcript. Upper panel, TEL/AML1 fusion transcript. Two different sizes of TEL/AML1 products are detectable (242 and 281 bp). To check integrity of the RNA, a 178-bp fragment of ABL was amplified from each patient (bottom panel). Lane M, 123-bp marker; lanes 1 to 9, patients no. 87086, 88615, 89100, 90568, 93437, 94112, 94565, 96526, 96569; lanes 10 to 12, water control for cDNA synthesis, first round of PCR, and second round of PCR; lane 13, positive control, REH cell line.