PTK2 and gastric cancer: Additional protein kinase that are frequently amplified in cancer include FAK (PTK2, 8q24, in 30% of ovarian cancers), the mTORC2 activator RICTOR (5p13.1) in epithelial malignancies, CDK4 (12q13-15) in sarcomas and glioblastomas, or CDK6 (7q21) in esophageal and stomach cancers.