[OS X Emacs] Font-lock for backquotes

[Emilie Vanvyve]

Hello,
When using the shell-script-mode, the syntax highlighting colors in pink any text enclosed in backquotes (e.g. var=`cat file.txt | head -n 1`). I would like to change the pink color to another one, but I couldn't find anywhere in the font-lock preferences where this is set up. I can adjust colors of practically everything apart from that one.
I would very much appreciate if anyone could let me know where this setting is kept.
With best wishes,
Emilie