The project was aimed at identifying deubiquitinases (DUBs) involved in cancer cell mechanosignaling. Lysates from cancer cells grown on collagen matrices with varying stiffnesses were incubated with an activity-based HA-tagged ubiquitin probe that covalently binds DUB active site. To identify DUBs differentially activated on soft and stiff collagen hydrogels, lysates were immunoprecipitated with anti-HA agarose beads. Immunoprecipitates were further identified by LC-MS/MS analysis.