PTK2 and cancer: The FAK signaling pathway is activated in several different cancers and multiple small molecule inhibitors of FAK have been developed, although only four small molecule inhibitors of FAK, including GSK2256098, VS-4078, VS-6062, and VS-6063 (defactinib), have been used in clinical trials for cancer therapy Sulzmaier et al. (2014), McLean et al. (2003), Mohanty et al. (2020).