Expression analysis of the C-MYB gene in T-ALL. (A) C-MYB transcript levels were quantified by RQ-PCR in a series of samples: normal bone marrow (BM, n = 2), PHA-stimulated PBL (PHA-PBL, n = 1), growing fibroblasts (n = 1), thymus (n = 1), t(6;7) TCRB-MYB cases (n = 5, one case not available), MYB^dup (n = 13), other T-ALL (n = 54) as indicated. Median value is indicated by a horizontal bar for each group. (B) Sequencing of C-MYB in TL92 tumor genomic DNA showed heterozygosity for a polymorphic T8/9 repetition in the 3′UTR region; sequencing of the TL92 leukemic cDNA in this TCRB-MYB case demonstrated a skewed allelic expression. (C) Analysis of the T8/9 polymorphic microsatellite using fragment size analysis. Heterozygous cases without C-MYB rearrangement (n = 27) showed balanced expression; heterozygous cases with t(6;7) translocation (n = 3; TL33, TL34, and TL92) showed a skewed expression of one C-MYB allele; and heterozygous cases with MYB^dup (n = 7) showed an imbalanced profile of both leukemic genomic DNA and leukemic cDNA.