As with many signal transduction pathways, plant gene expression during immune responses can be regulated by degradation. This often occurs when hormone binding to hormone receptors stimulates ubiquitin-associated degradation of repressor proteins that block expression of certain genes.  The net result is hormone-activated gene expression. Examples:
* Auxin: binds to receptors that then recruit and degrade repressors of transcriptional activators that stimulate auxin-specific gene expression.
* Jasmonic acid: similar to auxin, except with jasmonate receptors impacting jasmonate-response signaling mediators such as JAZ proteins.
* Gibberellic acid: Gibberellin causes receptor conformational changes and binding and degradation of Della proteins.
* Ethylene: Inhibitory phosphorylation of the EIN2 ethylene response activator is blocked by ethylene binding.  When this phosphorylation is reduced, EIN2 protein is cleaved and a portion of the protein moves to the nucleus to activate ethylene-response gene expression.