Moderate increase of BSAP protein synthesis in B lymphocytes carrying the t(9;14) translocation. The same amount (1 μg) of nuclear protein isolated from mononuclear cells of patient MLZ-1 or the indicated B-lymphoid cell lines was analyzed by EMSA assay for binding of BSAP to the paired domain recognition sequence of theH2A-2.2 gene. The radioactivity in the BSAP-DNA complex was quantitated by PhosphorImager analysis, and the BSAP expression level of the KIS-1 and MZL-1 cells is given relative to that of the control B cell lines BJA-B and Raji. PAX-5 is not expressed in the myeloma cell line RPMI 8226.