Although the mechanism of how these limonoids interfere with the NF-κB signaling pathway has to be investigated in more detail, our results indicate that TR4 and TR9 reduce NF-κB activity in hepatoma cells, resulting in decreased expression of NF-κB targets (Cyclin D1, Bcl2 or A20). This evidence concerns the gene NFKB1 and hepatocellular carcinoma.