I see the comment "GFP staining".  GFP or green fluorescent protein is
not a stain, it is a protein, when inserted into a cell, etc, that 
fluoresces with specific wavelength of UV light.  You can have the protein
in cells, fluorescing near or around the FITC excitation, but is best
viewed with GFP filters on the UV microscope.  It is visible with FITC
filters, but we found it much improved with the GFP filters.

You can do double fluorescence work, with GFP fluorescing on its own, then
perform immunoSTAINING on cells with a fluorescent label (in contrast to
the Green fluorescent protein) such as TRITC or Alexa 546 (Molecular Probes).

An example (from a publication on file) GFP in cells, and IFA - 
(immunofluorescent antibody staining) for GFAP glial fibrillary acid protein
to see live astrocytes in transgenic mice done on 40 um vibrotome section.
Very elegant!

Sorry to hog the day!

Gayle Callis