Overexpression of potassium channel ether à go-go in human osteosarcoma. Human ether à go-go (hEAG) potassium channels are primarily expressed in brain but also frequently overexpressed in solid tumors, which could indicate their potential value for cancer diagnosis and therapy. hEAG1, one member of the hEAG subfamily, has been shown to play a role in neoplastic process. Here we report the expression of hEAG1 in human osteosarcoma detected by a new polyclonal antibody. The full-length hEAG1 cDNA was cloned from human osteosarcoma cell line MG63 by RT-PCR and expressed in Escherichia coli as His tagged protein. The 6His-hEAG1F protein was purified by nickel agarose and used as the antigen to immunize rabbits following standard protocols. The obtained antiserum could detect hEAG1 exogenously expressed in HEK 293 cells. Furthermore, the polyclonal antibody was used to evaluate hEAG1 expression in 42 human osteosarcoma specimens and 19 osteochondromas specimens by immunohistochemistry. hEAG1 was expressed in 71.4% (30/42) osteosarcoma, and 15.8% (3/19) osteochondromas. Moreover, statistical analysis revealed that hEAG1 expression was not dependent on age, sex, site, histology, grade and type in the osteosarcoma specimens. Our data provide evidence that hEAG1 is overexpressed in human osteosarcoma and the hEAG1 polyclonal antibody offers a good tool for further characterization of the oncogenic function of hEAG1 in osteosarcoma.