RNA expression of BCL6 and its fusion partner genes in a series of B-cell lines at different stages of differentiation (top panel). Cell lines described in Table1. A mouse glyceraldehyde-3-phosphate dehydrogenase (GAPDH) probe was used to estimate the amount of blotted RNA. The genes that fused to BCL6 are labeled on the right. The different sizes of IGH, IGHG3, and IGL transcripts represent the products of physiological rearrangements of these genes.