Analysis of TRAIL-R2 promoter activity by luciferase assay. The TRAIL-R2 promoter region plasmid pDR5/SacI and empty vector pGVB2 were transfected into KOB, U937, K562, and HL60 cells. Cells were then incubated with or without 12.5 μg/mL BB-1 for 24 hours. Luciferase activity in 10 μg cell lysate was measured using luciferase assay reagents and a luminometer. Fold activation was obtained by setting the value for the empty vector control as 1.0. Each experiment was carried out in triplicate, and data are the mean ± SD. *P < .01.