What file is changed by GNOME if I change the language environment?

[Qingjia Zhu <qjzhupublic __NoSpam_yahoo ie>]

  From the 'Start Here' -> System -> Language, I changed my
  language enviroment, then I log out GNOME and logout bash
  and relogin bash, I found the $LANG was set to another value,
  I'm wondering what file was changed by GNOME to make such
  effective take place, because I found my .bashrc and
  .bash_profile remains that same, thanks.