I am posting my Flow Cytometry data here again because I realize that there are many people who are willing to help me, and I can learn a lot from you guys.

In this cell culture Lab, we use Cell U-937 Lymphoblast. And we want to learn how can we analyze cell cycle by using flow cytometry.

Could anyone help me to explain how to read the flow cytometry result related with cell cycle? I will be very glad to learn from you guys.

Thanks in advance! enter image description here


1 Answer 1


The basis of analysing flow cytometry data in regard to the cell cycle is the fact that DNA synthesis occurs in S-phase and therefore cells before S-Phase (G0/G1) have half the amount of DNA compared to cells after S-phase (G2). [M-phase lasts to short to be of any relevance for this kind of analysis]. Signals that have less DNA than the cells from G0/G1 phase are either artefacts or apoptotic cells with fractured DNA (these are labelled as sub G1).

In order to measure the amount of DNA per cell the dye PI (propidium iodide) is used, since its quantitatively binds to DNA. Therefore the distribution of the PI signal can taken as a distribution of the different stages of the cell cycle.

This wikipedia article also explains the analysis in more detail and provides further references.

  • $\begingroup$ Thanks for your response! And may I ask what represent the 100% Sub G1 in Unstained control? Is it also dead cell? or just a population of cell before undergoing cell cycle? @Nicolai $\endgroup$
    – Sokviseth
    May 31, 2017 at 7:08
  • $\begingroup$ @Sokviseth In an unstained sample none of the PI dye was added. Therefore you can not detected any DNA in these cells (even if it's there), so you can not say in which part of the cell cycle they are. This control is only done to check for problems with the PI staining. $\endgroup$
    – Nicolai
    May 31, 2017 at 7:30
  • $\begingroup$ Ah, I see :-). And i wonder one more thing why the amount of cells in (Dot Plot diagram) None is lower than that of Rapamycin (87.8 Vs. 91.4). Since the Rapamycin can inhibit the cell cycle, why the amout of cells do in crease? @Nicolai $\endgroup$
    – Sokviseth
    May 31, 2017 at 8:04

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