Figure 1. Expression of the COX-2/PGE2 pathway proteins in seven human breast cell lines leading to extracellular accumulation of PGE2.

MCF10A cells were compared to six human breast cancer cell lines. A. Protein lysates from MCF10A, MCF7, T47D, MDA-MB-468, MDA-MB-231, MDA-MB-436, and BT549 cells were blotted for the following proteins: COX-1, COX-2, EP4, MRP4, PGT, and 15-PGDH. β-actin was used as a loading control. Breast cancer subtypes are indicated below the blot by Normal (N), Luminal (L), and Basal (B). B. Conditioned media was collected from sub-confluent cell culture and assayed for PGE₂. Total PGE₂ (pg) in the conditioned media was normalized to total cellular protein (μg). * p < 0.01 relative to the other four cell lines. PGE₂ content is expressed as mean ± SEM of triplicate determinations.