Updated project metadata. To study the effect of microbe-associated molecular pattern (MAMP) treatment (flg22) on the phosphorylation of nuclear proteins, we treated Arabidopsis plants with flg22 and after isolation of nuclear proteins, we enriched for phosphopeptides and then carried out LC-MS/MS analyses. We used statistical analysis tools to identify differentially phosphorylated proteins in response to MAMP treatment in the mock and treated samples.