PTK2 and neoplasm: Focal adhesion kinase (FAK), a critical tyrosine kinase downstream of the focal adhesion and extracellular matrix signaling pathways, is closely related to tumor cell motility.[23] Notably, COA4 manipulation did not alter total FAK protein levels; however, COA4 knockdown significantly reduced FAK phosphorylation, while overexpression markedly increased it (Figure S4I, Supporting Information).