Figure 1. Transcriptional bursting and trans‐acting factors are two distinct causes of cell‐to‐cell heterogeneity.

1. Cartoon depicting that different cells can have different activities of trans‐factor (TF) regulatory molecules in addition to the effects of transcriptional bursting.
2. Simulated data showing that variability from shared regulatory factors results in correlation between two genes with three example cases: intrinsic dominated noise (top three panels), mixture of cell state and allele‐specific sources (middle three), and cell state dominated (bottom three). This correlation is diminished when the expression levels are conditioned on the levels of these shared regulatory factors (middle and right). After conditioning on all trans‐acting regulatory factors, the remaining variability due to transcriptional bursting alone is potentially significantly smaller (right). Inset text is the Pearson correlation coefficient between gene A and gene B (brown) and the Fano factor of gene A (blue).