Indeed, the recent observationthat TTR expression can be induced in human neuroblastoma SH-SY5Ycells, primary hippocampal neurons from APP23 mice, and adult APP23hippocampi (but not mouse liver or cultured hepatoma cells), followingthe activation of the heat shock response, is supportive of the hypothesisthat TTR plays a key role in maintaining neuronal protein homeostasisand hence in protecting against neurodegeneration.21 This evidence concerns the gene TTR and hepatocellular carcinoma.