PTGS2 and melanoma: Administration of 1 μg/ml celecoxib to B16M 30 min prior to BMSC-CM completely abrogated (P < 0.01) adhesion-stimulating activity of both untreated and LPS-treated BMSC-CM (Figure 4A), indicating that BMSC factors upregulated the ability of activated melanoma cells to adhere to BMSCs via COX-2-dependent VLA-4 expression.