Northern analysis of NRG expression. (A) Hybridization using a NUP98 cDNA probe. (B) Hybridization of the same membrane with a RAP1GDS1 cDNA probe. (C) 18S rRNA from the ethidium bromide-stained gel before transfer. RNA was isolated from 2 normal controls (C1 and C2) and from the 3 patients (P1, P2, and P3). pres is a presentation sample, rem is a remission sample, and rel is a relapse sample. Each lane contains 5 μg of total RNA from peripheral blood mononuclear cells, except that P1 rem contains 5 μg of total RNA from bone marrow. The lane marked m is a RNA ladder (Promega). The band in this lane in (C) is marker and not 18S RNA. N indicates theNUP98 4.05- and 7.25-kb bands. The 7.25-kb band is a precursor that also contains the NUP96 coding sequence.47 RG indicates the 2.8- and 4.1-kb RAP1GDS1 bands. NRG indicates the 4.4-kb NRG transcript. NRG2 in patient no. 3 is not indicated, because it is not distinguishable from the 4.05-kbNUP98 and 4.1-kb RAP1GDS1 bands. The arrowheads indicate higher molecular weight transcripts that hybridize with both the NUP98 and RAP1GDS1 probes.