Expression and function of IL-12R in MM cells. (A) Top panel: IL-12RB2 expression in MM cell lines as assessed by RT-PCR. MW indicates molecular weight; NC, negative control (water in place of cDNA); PC, positive control (total tonsil B cells); different MM cell lines (LP-1, U266, JJN3, Karpas 620, RPMI 8226, H-Sultan, OPM-2, XG-1, XG-6, and HCI-H929) are shown. Bottom panel: Methylation specific PCR analysis of MM cell lines. MM cell lines that do not express the IL-12RB2 mRNA (LP-1, U266, Karpas 620, RPMI8226, H-Sultan, and OPM-2) show the amplification band corresponding to the methylated target sequence, whereas MM cell lines that express IL-12RB2 mRNA (XG-1, XG-6, and NCI-H929) failed to amplify the methylated sequence. (B) IL-12RB2 expression in NCI-H929 and XG-1 MM cell lines, as assessed by flow cytometry using the anti IL-12Rβ2 antibody from Santa Cruz. Open profile represents IL-12Rβ2 staining; dark profile, isotype-matched antibody staining. (C) Left panel: IL-12Rβ2 protein expression in NCI-H929 cells cultured with medium alone or with hrIL-6 for 48 hours, as assessed by flow cytometry using the Santa Cruz antibody. Right panel: Quantitative analysis of IL-12RB2 versus GAPDH transcript in the same NCI-H929 cell suspensions analyzed in the left panel, cultured with (□) or without (■) IL-6. (D) Angiogenic activity of supernatants from NCI-H929 (top panels), XG-1 (middle panels), and U266 (bottom panels) cells cultured in the presence or absence of hrIL-12, as assessed by CAM assay.