MMP9 and melanoma: Numerous studies have suggested that epithelial-to-mesenchymal transition (EMT) contributes to early-stage dissemination of cancer cells and is pivotal for invasion and metastasis of melanoma.12,13 Matrix metalloproteinases (MMP2, MMP9) play vital roles in tissue remolding and cancer metastasis.14 As shown in Figure 3(a), mesenchymal-related gene (N-cadherin and E-cadherin), invasion-and metastasis-related gene (MMP2 and MMP9) expression in melanoma cells were significantly decreased after Piezo1 inhibition compared with control group.