RT-PCR with primers detecting NPM-ALK transcripts. Total mRNAs extracted from the t(2; 5)-bearing SU-DHL1 cell line (lane C+) and a t(2; 5)-positive case of ALCL (lane 2) yield the expected band of 98 bp. RNAs from the CEM T-cell line (C−), a t(2; 5)-negative ALCL (lane 1) and from two tumors under study (cases 1 and 6) (lanes 3 and 4) are negative for hybrid NPM-ALK mRNA. NoT, no template cDNA; MW, molecular-weight markers.