PTGS2 and cancer: In human cancer specimens, it has been observed that COX-2 and/or mPGES-1 are constitutively expressed in non-small cell lung cancer [52,53], colorectal cancer [54,55], breast cancer [56,57,58], prostate cancer [59,60], melanoma [61,62], and hepatocellular carcinoma [63,64], and contribute to tumor aggressiveness.