The PRAD1 gene identified from the chromosome band 11q13 region was previously demonstrated to be overexpressed in cell lines with t(11;14)(q13;q32) translocation and was suggested to be a candidate BCL-1 gene. We report here one case of mantle zone lymphoma with a t(11;22)(q13;q11), a variant translocation at the BCL-1 locus, having the PRAD1 overexpression. By analogy with the c-myc gene in Burkitt's lymphoma and the BCL-2 gene in follicular lymphoma, this case supports strongly the idea that the PRAD1 is the candidate BCL-1 gene.