NAP1 is known to be phosphorylated on several sites by TBK1. We decided to identify the phosphorylation sites on NAP1. For this, using an anti-GFP antibody, we immunoprecipitated a version of NAP1 fused to the GFP protein at its amino terminus (GFP-NAP1) from HEK293T cells co-expressing GFP-NAP1 and TBK1 fused to the mCherry protein at its amino terminus (mC-TBK1). Immunoprecipitates were analyzed by SDS-PAGE and WB, and the bands corresponding to NAP1 were cut and digested by trypsin protease before analysis by LC-MS/MS.