Variations of proline-rich kinase Pyk2 expression correlate with prostate cancer progression

Proline-rich kinase 2 (Pyk2), also known as CAK beta (cell adhesion kinase beta), is a cytoplasmic tyrosine kinase that is structurally related to foc al adhesion kinase. Pyk2 is expressed in different cell types including bra in cells, fibroblasts, platelets, and other hemopoietic cells. Pyk2 is rapi dly tyrosine phosphorylated in response to diverse extracellular signals ac ting via different post receptor pathways. We have investigated whether thi s protein kinase is functionally expressed in normal and neoplastic prostat e tissues. In this study, we demonstrate that Pyk2 is expressed only in nor mal epithelial prostate tissue and in benign prostatic hyperplasia, whereas its expression progressively declines with an increasing grade of malignan cy of prostate cancer.