A–B. PC3-M, C4-2B (A), and LNCaP cells (B) were plated in 6 well plates and allowed to attach and spread. LNCaP cells were transfected with control siRNA or PG siRNA (a pool of 4 sequences). PC3-M, C4-2B, and LNCaP cells were treated with medium containing PP2 (10 µM) or DMSO (solvent control) for 24 hours prior to performing the dispase assay. Inhibition of Src strengthens cell-cell adhesion in PCa cells in general and is able to rescue cell-cell adhesion in PG-deficient cells. C. PC3-M and ARCaPM cells were plated in 24-well plates and allowed to attach and spread. The cells were treated with medium containing the selective Src- family kinase inhibitor PP2 (10 µM) or DMSO (solvent control) for 24 hours prior to performing the scratch wound assay. D. ARCaPE cells were plated in 24-well plates and allowed to attach and spread. The cells were transduced with GFP-containing adenovirus or caSrc-containing adenovirus, and after 24 hours a scratch wound was made. Activity of Src is directly correlated with motility of PCa cells. E. ARCaPM, PC3-M, and LNCaP cells were plated in 6-well plates and allowed to attach and spread. LNCaP cells were transfected with control siRNA or PG siRNA pool and after 96 hours, the cells were lysed. ARCAPM and PC3-M cells were transduced with GFP-containing adenovirus or PG-containing adenovirus, and after 24 hours the cells were lysed. The lysates were subjected to SDS-PAGE followed by immunoblotting with antibodies against PG, pSrc, Src, and GAPDH. Levels of pSrc were determined by normalizing to Src levels for each cell line using Image J. Phosphorylation (activation) of Src is inversely correlated with PG levels. Representatives of at least three independent immunoblots are shown, with numbers representing GAPDH normalized pSrc/Src ratio for the blot shown. The average ratio and standard deviation of pSrc/Src normalized for loading by GAPDH is as follows: ARCaPM 0.6+/−0.2, LNCaP 1.7+/−0.2, PC3M 0.7+/−0.1. Graphs represent averages +/− SEM. *P<0.04; **P<003; ****P<0.0001, by paired Student t test.