The EGFP gene driven by the immunoglobulin heavy chain variable region (VH) and a floxed neo cassette were inserted 1.5 Kb upstream of the first non-coding exon. The VH-EGFP reporter gene is in the opposite orientation of Myc. This allele serves as a reporter of chromosomal T(12;15) translocation in B lymphocytes and plasma cells. (J:162138)