PTGS2 and melanoma: In this study we have correlated the expression level of COX-2 in samples from canine patients with established markers linked to poor prognosis, and we describe the development of two melanoma cell lines with stable integration of a doxycycline-regulated expression vector containing a COX-2 targeted micro-RNA (miRNA), to enable us to reversibly suppress endogenous COX-2 gene expression.