R help - Oct 2011 - How to change font family in a levelplot using Lattice

Dear R users:

I want to assign a global font family to a levelplot such as
par(family="serif") in traditional plotting. However, I can only
change part of the text using

panel.text(x,y,"A",fontfamily="serif")
or scales=list(fontfamily="serif") to change the axis number font
family.

How can I change the font family of xlab and ylab and the numbers shown on the
legend of the levelplot?

Thanks in advance,
Bingzhang