KDE and .profile/.bash_profile

A possible solution is a ~/.xsession file like this (mostly what you'd put into your ~/.bash_profile except for the final exec):
#!/bin/sh

export LANG='en_US.UTF-8'

# set PATH so it includes user's private bin if it exists
if [ -d ~/bin ] ; then
    PATH=~/bin:"${PATH}"
fi

exec /usr/bin/x-session-manager