Reactome events (pathways and reaction-like events) undergo internal review by a member of the Reactome editorial staff and external review by a domain expert. Events that undergo both internal and external review are assigned the highest review score of  5. When such an event is revised and the revisions result in *structural modification to that event, the event’s review score is demoted to 3. The revised event must be internally reviewed again to attain a review score of 4 and externally reviewed to regain a score of 5. The table below summarizes the definitions of each review status.

Status-based release of Reactome content

Review Score


Release status

1 Restructured after internal review NOT RELEASED
2 Restructured after external review NOT RELEASED
3 Internally reviewed, awaiting external review RELEASED
4 Restructured after external review, then internally re-reviewed RELEASED
5 Externally reviewed RELEASED

*What is a structural modification to an event?

A structural update involves at least one of the following modifications after the initial internal and/or external review of the event.

  • Addition, removal, or replacement of a CatalystActivity, Regulator, Input, Output of a reaction-like event
  • Addition, removal, or replacement of an Event of a pathway

Any one or more of these changes to an event demotes its review status and requires additional review as described in the table above in order to restore its review status.

A Reactome event that has been internally reviewed and is still awaiting an external review after six months is publically released with a score of 3. Once reviewed, it is assigned the maximum score of 5.If an event with a score of 3 is *structurally modified, its score is demoted to 1 and must be internally reviewed to regain its original score of 3.  If an event with a score of 4 is structurally modified, it is demoted to a score of 2 and must be internally reviewed to recover its score of 4 and externally reviewed to raise its score to 5 . Reactome does not include events with a score lower than 3 on the public website.

Where can I see the review status of a Reactome event?

The review status of an event can be seen in the upper right corner of the  Pathway Browser details panel:

ReviewStatus 1

 and also on the content details page reached via the search:

ReviewStatus 2