I'm currently doing cell cycle analysis to reveal dead cells via the SubG1 fraction (one aspect of several other apoptosis assays I do).I do the following PI staining protocol:
- Induce cell death
- harvest cells (adherent cells)
- resuspend pellet in staining solution (0.1% Triton X-100, 50ug/ml PI, 0.5x PBS).
- keep on ice until flow cytometry
I get a real nice cell cycle if I don't induce cell death. I observe a strange cell population in the samples where the cells start do die.
This population is someting between the S-Phase and G2-phase population (see image). In the FSC/SSC plot they appear as a very low SSC and medium FSC population. Have you ever seen this?
This is the control = No cell death induction
Here I induced cell death: