Software :: GNU Screen Doesn't Start Shells As A Login Shell?

I want to have an ls' output colorization in gnu screen. Colorization in my system (Slackware 13) is realized by aliasing of ls in /etc/profile.d/coreutils-dircolors.sh:

Code:
$ alias ls
alias ls='/bin/ls $LS_OPTIONS'
where $LS_OPTIONS is
Code:
$ echo $LS_OPTIONS
-F -T 0 --color=auto

But in screen this alias isn't defined. It seems like /etc/profile script isn't executed at shell starting in screen. I think it happens because screen starts a shell not as a login shell. I tried to correct it by adding to ~/.screenrc or to /etc/screenrc. The problem is the same. By the way when I start screen as a root I haven't this problem. What's wrong?