Examination of expression of the checkpoint and cell cycle related proteins; p-CHK2, CHK2 (checkpoint), Cyclin B1 (G2/M marker), Cyclin D1, CDK4, p27, and p21 (G0/G1 marker), and CDC25A, Cyclin E1, CDK2 (S phase entry marker) in the cultures of (A) PC3 cells and (B) DU145 cells following docetaxel treatment with the presence or absence of GAS6 by Western blots.