NF-κB is also a transcriptional regulator of cyclooxygenase-2 (COX-2) (63), whose activity showed a strong correlation with P-gp expression in hepatocellular carcinoma (64) and colorectal cancer (65), and with multidrug resistance protein 4 (MRP4) in lung cancer (66). The gene discussed is PTGS2; the disease is colorectal cancer.