PTK2 and melanoma: Integrins are composed of α and β subunits, and the engagement with ECM ligands triggers intracellular signaling cascades in melanoma, including the following: (1) Focal adhesion kinase (FAK) pathway, in which integrin-mediated adhesion activates FAK, which in turn phosphorylates downstream effectors such as Src kinase, PI3K/Akt, and ERK1/2, promoting cell migration, survival, and proliferation [74].