mRNA expression of proangiogenic factors by myeloma cells. RT-PCR was performed to test angiogenic factor mRNA expression by HMCLs (RPMI 8226, OPM-2, U266, XG-1, and XG-6), purified MM cells, and BMSCs obtained from patients. β₂-Microglobulin was amplified as internal control. MG-63 was used as positive control (CON+) for bFGF, TGF-β, and HGF, whereas BMEC-60 was used for VEGF, PDGF and IL-8. MNCs from healthy subjects were used as negative control (CON-).