PTK2 and esophageal squamous cell carcinoma: Activated FAK or SFKs can function as addictive oncoproteins to mediate ESCC malignancy, and by targeting FAK and SFKs, the malignancy of such solid tumors can be effectively blocked.36,37 However, studies on how FAK and SFKs synergistically mediate the progression and lymph node metastasis of ESCC cells are limited.