PTK2 and colorectal cancer: For example, overexpression of FAK protects 3D grown head and neck squamous cell carcinoma (HNSCC) cells from radiation-induced cell death [118], while siRNA-mediated silencing or pharmacological inhibition of FAK increases the radiosensitivity of different tumor cell lines from pancreatic cancer [112], breast cancer, colorectal cancer [119], and HNSCC [45, 55].