MyD88-dependent B7-H1 expression in MM cells. (A) Flow cytometric analysis of B7-H1 expression in RPMI 8226 cells and in 5 CD138-selected MM samples after incubation for 24 hours with 500 IU/mL IFN-γ and transfection with NS, MyD88, or TRAF6 siRNAs. (B) Time-course analysis of B7-H1 expression after addition of 500 IU/mL IFN-γ by RPMI 8226 cells transfected with MyD88 or DN-hMyD88 cDNA. (C) B7-H1 expression in RPMI 8226 cells transfected with DN-MyD88 or a control plasmid and incubated for 24 hour with TLR ligands (500 ng/mL LPS, 2.5 μg/mL PGN, 5 μM ODN). (D) B7-H1 expression in 23 CD138-selected MM samples incubated with TLR ligands. (E) ERK1/2 phophorylation in RPMI 8226 or RPMI 8226/DN-hMyD88 cells treated for 30 minutes with TLR ligands with or without 20 μM UO126.