Figure 1.

Effects of mithramycin on gliostatin/thymidine phosphorylase (GLS/TP) promoter activity based on deletion constructs. Closed ovals indicate Sp1-binding sites. Open ovals indicate interferon-stimulated response element (ISRE) and gamma-activated sequence (GAS) sequences. Fibroblast-like synoviocytes were transiently transfected with deletion constructs and then incubated with mithramycin (100 nM, shaded column, or 300 nM, closed column) for 24 hours. Control cells were incubated without mithramycin (open column). Data were normalized by measuring the luminescent reaction of the internal control. Results are presented as mean ± standard error of the mean of five determinations. Statistical significance was calculated by using the Mann-Whitney U test: compared with samples without mithramycin *P < 0.05, **P < 0.01; compared with samples with pTP-Luc1 without mithramycin ^†P < 0.01.