bFGF expression by HMCLs and by MM patients. RT-PCR was performed in order to test bFGF mRNA expression in HMCLs (RPMI-8226, OPM-2, U266, XG-1, and XG-6) and bone marrow stromal cells (BMSCs) obtained from patients with MM. β2-microglobulin was amplified as internal control. K562 and mononuclear cells (MNCs) from healthy subjects were used as positive and negative control, respectively (A). HMCLs (10⁶/mL) were incubated in the presence or absence of IL-6 (20 ng/mL). bFGF protein was assessed either in cell lysates by Western blot analysis after 24 hours (B) or in conditioned medium by ELISA after 48 hours (C). (D) bFGF immunostaining in BM biopsies of 2 representative patients with MM with negative (left) and positive (right) myeloma cells performed with anti-bFGF polyclonal Ab (25 μg/mL) using indirect immunoperoxidase detection method.^6,7  Endothelial cells are the internal positive control. Original magnification, × 100.