PTK2 and neoplasm: Abnormal expression of PTK genes, such as insulin-like growth factor receptor (IGF-IR), epidermal growth factor receptor (EGFR), focal adhesion kinase (FAK), or the proto-oncogenes RET and NyK/mer, has been shown to correlate with progression in a variety of tumours (Luttrell et al, 1994; Liu et al, 1995; Resnik et al, 1998).