Currently,long-standing problems in traditional chemotherapy are the severe side effects.Antimicrobial peptides have received increasing attention as potential antitumor drugs due to their new mode of action.[1] To increase the tumor selectivity of antimicrobial peptides,we designed a new type of acid-activated antimicrobial peptide AMitP by conjugating antimicrobial peptide MitP to its anionic binding partner MitPE via a disulfide linker[2].AMitP showed significant antitumor activity in a pH-dependent manner,suggesting it can be activated under the tumor acidic environment.