Part I: In RKO cells, we knocked down PPM1L and immunoprecipitated exogenously expressed PD-L1 for subsequent mass spectrometry sample processing and analysis, aiming to profile the altered PD-L1 interactome. Part II: Following PPM1L depletion in RKO cells, proteins were harvested and phosphopeptides were enriched using Fe-NTA technology prior to mass spectrometric analysis.