Help a novice : ALP stability after fixation - (Apr/21/2010 )

Hi, I´m fixating MC3T3 cells in cold formaldehyde and then store samples in PBS. Later I want to stain these cells for ALP. Do you know how long time you can wait with the staining? Will ALP activity decrease with time? Do I have to stain immediately after fixation?

I´m a student quite new to cell biology, so any help is appreciated!

Erik

Formaldehyde fixes the proteins so that they are stable. The fixation will degrade over time in PBS, so that your cells will only stay fixed for a week or two. For long term storage, dehydrate your cells progressively in 25%, 50%, 75%, 100% methanol and store at -20 deg C. To use after this , rehydrate the cells using the reverse sequence of methanol.