Similarly, the combination treatment with ALA-PDT and celecoxib, an anti-inflammatory drug that inhibits prostaglandin-endoperoxide synthase 2 (PTGS2) (a downstream target of HIF-1 and NF-κB), yielded an additional 40 % reduction in tumor growth compared to ALA-PDT alone in human cholangiocarcinoma (HuCC-T1)-bearing mice [38]. This evidence concerns the gene PTGS2 and cholangiocarcinoma.