Use this calculation for cell-culture or microscopy observations collected with one counting rule, assay gate, calibration, and unit convention. It is suited to documenting dilution, growth, labeling, geometry, or population fractions.

S phase cells

An integer count greater than or equal to 0.

Total cells

An integer count greater than or equal to 0.

The implementation follows this calculation rule: Compute the fraction of cells in S phase relative to the total counted cell population.

S phase fraction

The calculated s phase fraction.

Counts and fluorescence measurements can be biased by clumping, debris, segmentation, gating, background signal, saturation, sampling fields, or unequal viability. A calculated percentage does not identify the biological mechanism behind a change. Ratios and percentages become unstable when their denominator is small, uncertain, or defined differently between samples.

Retain representative images or cytometry plots and include biological replicates. Orthogonal viability, proliferation, apoptosis, or direct counting assays can distinguish effects that a single cell metric conflates.

• G1 Percentage

  Compute the percentage of cells in G1 phase relative to the total counted cell population.

• M Phase Percentage

  Compute the mitotic fraction of a cell population as a percentage of cells in M phase.

• BrdU Incorporation Rate

  Compute the percentage of BrdU positive cells relative to the total counted cell population.