Psalmotoxin 1 (PcTx1) is a protein toxin that can bind at subunit-subunit interfaces of acid-sensing ion channel 1a (ASIC1a). Psalmotoxin 1 is a potent and slective ASIC1a inhibitor (IC50: 0.9 nM) by increasing the apparent affinity for H+ of ASIC1a. Psalmotoxin 1 can induce cell apoptosis, also inhibits cell migration, proferliration and invasion of cancer cells. Psalmotoxin 1 can be used in the research of cancers, or neurological disease.