USP4 and Salmonella Infections: Activity-based chemical proteomics allows for monitoring of activity of multiple DUBs in infected cells, and we chose this technique to not only discover novel chicken DUBs that were previously uncharacterized, but also to unravel DUBs that are differentially regulated in Salmonella infection, which included USP4, USP5, UCH-L3 and UCH-L5.