Ethanol fixsation and sub-G1 population

Hello everyone,

I would like to measure the size of the sub-G1 population on
logarithmic scale as well as distribution of cells in the cell cycle
on lineary scale, by collecting the fluroscence of PI staind cells in
FL3 and FL2.

In this laboratory, they fixate cells in formaldehyde according to a
well establish protocol for measurement of the sub-G1 population. I
understand from the archives of this list, that the broad G1 and G2
tops I see are due to the formaldehyde.

Is there any reason why one should prefer formaldehyde over ethanol
fixation? Does use of formaldehyde yield beter apoptosis data? The
focus is measurement of of the sub-G1 population, analysis of cell
cycle distributionwould just be a nice bonus.

Heres the protocol in brief:
Incubate with 2% formaldehyde on ice for 30 min
Remove formaldehyde and incubate with ethanol on ice for at least 15 min
Remove ethanol and incubate with RNAse for 30 min at 37 degree
Remove RNAse and add PI

Thank you in advance for any help/thought on this matter
Ulrik