Expression of mRNA encoding for CD138/syndecan-1 in primary tumor cells from a patient with PEL (patient no. 1), human PEL-derived cell lines (CROAP-2, BCBL-1, BC-1, BC-2, and HBL-6), the human myeloma cell line U266, and myeloid leukemia cells KG-1A, as detected by RT-PCR analysis. cDNA bulks were prepared and amplified with specific primers for human syndecan-1 (upper panel) and β-actin (lower panel). Ten microliters of amplified cDNAs was also run on 1.5% agarose gels, blotted onto nylon membranes, and hybridized with a syndecan-1–specific cDNA probe (center panel).