Differential modulation of CXCR3 ligand release by the COX-2 specific inhibitor celecoxib. MCF-7 and MDA-MB 231 cells were preincubated with the indicated concentrations of celecoxib 30 minutes prior to IFN-γ addition (50 ng/mL for MCF-7, 2.5 ng/mL for MDA-MB 231). After 24 hours, cell supernatants were collected and CXCR3 ligand concentrations measured by ELISA. (a and b) In MCF-7 cells, celecoxib increases CXCL9 and CXCL10 release at low concentrations (0.1 and 1.0 μM), but this increase deminishes at higher concentrations. (a and c) At 30 μM celecoxib a significant reduction in CXCL9 secretion was seen. (d) The CXCL10 release from MDA-MB 231 cells rises in a dose-dependent manner with increasing celecoxib concentrations. Asterisks mark significant differences compared with the control, if not indicated otherwise.