Only one myeloma cell line produced high Sema4D (MR20: 104.45 ng/ml) compared to all others (mean ± SD: 1.6 ± 1.4 ng/ml), while there were undetectable Sema4D levels in the supernatants of all ovarian cancer cell lines (Fig. 1a). This evidence concerns the gene SEMA4D and plasma cell myeloma.