FACS of GFP expressing cells from mice brains - (Jun/08/2009 )

Hi everyone,

I'm working on adult mice brains expressing GFP in certain cells. I would like to see the GFP expressing cells by FACS.
The procedure i've tried so far was cutting the brains and then transferring it through a 100 micron strainer using a syringe plunger.
Then i've incubated the cells with the primary ab (red/APC), washed (PBS/BSA/Azide) and in the end the cells were resuspended in PBS/Azide/Paraformaldehyde.
Unfortunately, I can hardly detect any GFP expressing cells (although I know they were there). I've tried not using any paraformaldehyde at the end but it made not difference.
Does anyone have any ideas? A different procuedure?

Thanks very much in advance

Have you looked at them under a fluorescent scope to make sure the GFP hasn't leaked out of the cell before you go to the FACS?