Ac-YVAD-CHO (L-709049) acetate is a potent, reversible, specific tetrapeptide interleukin-lβ converting enzyme ( ICE ) inhibitor with mouse and human K i values of 3.0 and 0.76 nM. Ac-YVAD-CHO acetate is also a caspase-1 inhibitor. Ac-YVAD-CHO acetate can suppress the production of mature IL-lβ.