UVB-induced EP2 and EP4 expression was diminished in COX-2−/− mice. A, mice were sacrificed 24 h after UVB irradiation (5.0 kJ/m2), and 50 μg of protein was electrophoresed. Membrane was probed with antibodies for EP1, EP2, EP3, and EP4. Two WT and two COX-2−/− mice were used, and each lane represents an individual mouse. The experiment was repeated with similar results. B, fold change of each EP receptor in unexposed and UVB-exposed WT and COX-2−/− mice. Mean densitometry values for replicates of each EP receptor were normalized to actin.