Thallium (Tl) is one of the most toxic heavy metals and is found ubiquitously in the earth's crust. To investigate the cellular responses to and against Tl cytotoxicity, we conducted DNA microarray analysis using three human cell lines of different origins: SH-SY5Y (neuroblast-derived), HEK293T (embryonic kidney-derived), and Huh-7 (hepatoma-derived) cells. All of the ten genes that showed the highest inductions in Huh-7 cells treated with 60 µM Tl