Fold enrichment is a measure of the specific signaling activity for each identified kinase. This value is calculated as the ratio of significant targets for a specific kinase (relative to the total number of significant sites) divided by the proportion of that kinase’s total known targets within the entire background dataset (i.e. expected frequency).
- k: Number of significant phosphosites targeted by Kinase X.
- n: Total number of significant phosphosites in the experiment.
- K: Total known targets of Kinase X in the entire database (e.g., PhosphoSitePlus).
- N: Total number of phosphosites in the background (the “universe”)
A high fold enrichment value suggests that the kinase’s activity is being strongly and specifically modulated in your experimental condition.