The ADP-Ribosylation Cycle Inhibitor Mix is a 500x cocktail of two inhibitors (AZD2281 and PDD). AZD2281 (Olaparib) is a PARP inhibitor with broad pan-PARP activity, which blocks a large proportion of the ADP-ribosylation of proteins. PDD is a potent, selective poly (ADP-ribose) glycohydrolase (PARG) inhibitor that blocks PARG-mediated de-ribosylation of proteins. Used together, these two inhibitors “freeze" the state of cellular ribosylation at the time the mix is applied to the cells. This product is designed to supplement a cell lysis buffer of choice to prevent post-lysis changes in the ADP-ribosylation status of extracted proteins.