"Twin-peak" @ G2/M phase? - funny result of cell cycle assay (Jul/02/2008 )

Hello,

I have recently gotten some funny cell cycle histograms with a human cell line - a "twin-peak"/ "fork-headed" @ g2/M

I wonder if anyone encounter this in PI (Propidium Iodide) staining before??? it was a normal setup, e.i. without drug or any treatment. please advice if you could share your insight

I once had a similar problem and it turned out to be caused by accidently mixing two different types of cells I was growing. But in that case, both the G1 and G2 peaks were doublets.

All I can suggests is to check the gating for light scatter. if there is a great deal of doublet G1 cells, they may fluoresce slightly differently than a G2 singlet.