sentence: Of note , E234G HYPE-mediated AMPylation of its putative substrate histone H3 was shown to be inhibited by Ap4A in vitro [ 7 ] , presumably via an ATP-competitive mode of action.Employing similar selection criteria as with the activators , we isolated eight inhibitors ( I1 – I8 ) for follow-up investigation ( Figure 10A Figure 11A and Figure 12A – H , Table 3 ) .