ALLM (Calpain Inhibitor) is a cell-permeable, peptide aldehyde inhibitor of calpain I and calpain II. ALLM acts as a very potent inhibitor of cathepsin L and the strongest inhibitor of cathepsin B amongst the peptide aldehydes. This compound inhibits the processing of malaria aspartic hemoglobinases plasmepsins I and II?in vitro. ALLM also inhibits other neutral cysteine proteases, and activation-induced programmed cell death. It restores defective immune responses in HIV+ donors. ALLM blocks nitric oxide production by activated macrophages by interfering with transcription of the inducible nitric oxide synthase gene. ALLM also acts as a weak inhibitor of proteasome.