['To investigate the effects of HBx gene on proliferation activity of hepatoma cells in vitro and in vivo.', 'The plasmid pHA-HBx carrying HBx gene was transfected into HepG(2) cells, and the positive clones were screened and identified with G418 and RT-PCR, respectively. The growth curve and population doubling time were calculated, and the cell cycle was analyzed by flow cytometry (FCM). The proliferation activity of transformed cells was measured with (3)H-TdR incorporation rate and nude mice model in vitro and in vivo.', 'The result of RT-PCR indicated that HBx gene was integrated into the genome DNA of HepG(2) cells and transcripted. The growth curve and population doubling time showed a high proliferation activity of transformed cells. The amount of cells at stage S and G(2)/M were significantly higher, and cells at stage G(0)/G(1) were lower than those in control group. The tumors developed from transfected cells grew much quicker than those developed from HepG(2) cells in nude mice model.'] Does [ HBx gene facilitate the proliferation activity of hepatoma cells in vitro and in vivo ]?