Figure 3. The anti-tumor mechanism of PcTx1. PcTx1 can suppress activation of ERK1/2 by inhibiting ASIC1 channels, followed by upregulating p21 and p27 protein expression to arrest the cell cycle. The level of p21 mRNA increases, but that of p27 mRNA does not change. The inhibition of ERK1/2 phosphorylation also restricts migration, but the mechanism remains unclear. ASIC1: Acid-sensitive ion channel 1; PcTx1: Psalmotoxin1.