To determine whether morphine treatment exaggerates the expression of COX-2, we evaluated COX-2 protein and mRNA expression in SCK mammary tumours in A/J mice after 13 days of treatment using Protocol I. Cyclooxygenase-2 protein and mRNA levels were increased by five- to seven-fold after morphine treatment as compared to PBS-treated mice (Figure 1A and B). The gene discussed is PTGS2; the disease is breast cancer.