Northern blot analysis of 10 μg total RNA from various cell lines of B-cell lineage. ASLCL, an EBV-transformed normal B-lymphoblastoid cell line acted as negative control. Both a truncated 6.3-kb and the 4.2-kb BCL9 transcript were overexpressed in the CEMO-1 cell line but not in any other B-cell lines with 1q21 abnormalities (Table 1).