DEK protein level is a biomarker of CD138.sup.positive normal and malignant plasma cells

Overexpression of DEK oncogene is associated with increased proliferation of carcinoma cells and it is observed in several solid tumors due to the amplification of the 6p22.3 chromosomal region where DEK locates. Although the same chromosomal amplification occurs in multiple myeloma (MM), a plasma cell neoplasm, whether the expression and the copy number of the DEK gene are affected in MM remains elusive. We show that despite the increased copy number in CD138.sup.positive MM cells (4 out of 41 MM samples), DEK mRNA expression was down-regulated compared with that in CD138.sup.negative bone marrow (BM) cells of the same patients (P