Figure 3. Pharmacologic inhibition of MRP4 with Tyrphostin AG1478 or MK571 suppresses PGE2 export.

A. MDA-MB-231 cells were stimulated briefly with 80 nM PMA before the media was replaced with the indicated concentrations of A. Tyrphostin, B. MK571, or DMSO. MDA-MB-436 cells were treated with the indicated concentrations of C. Tyrphostin D. MK571, or DMSO. PGE₂ accumulation in the conditioned media after 18 hours was quantified by enzyme immunoassay. PGE₂ is expressed as mean ± SEM pg/μg protein from triplicate determinations. * p < 0.05, ** p < 0.01*** p < 0.001 relative to DMSO.