Deng et al. showed that CD133 expression was downregulated by celecoxib in two colon adenocarcinoma cell lines with different statuses of cyclooxygenase-2 (COX-2), DLD-1 (COX-2 negative) and HT29 (COX-2-positive) [197]. The gene discussed is PTGS2; the disease is colon adenocarcinoma.