Interplay between RhoA/ROCK and Src kinase signalling. (a) Primary mouse chondrocytes were incubated for 1 to 3 days with dimethyl sulphoxide (DMSO) or the Src inhibitor PP2 (10 μmol/l), and Ras homology A (RhoA) activity was measured using the G-LISA™ kit (Cytoskeleton). No significant differences in RhoA activity were observed upon Src inhibition (n = 3). (b) Primary mouse chondrocytes were incubated for 1 or 2 days with DMSO or the Rho-associated, coiled-coil containing protein kinase (ROCK) inhibitor Y27632 (10 μmol/l) or the actin-modifying drugs cytochalasin D (1 μmol/l) and jasplakinolide (50 nmol/l). Expression levels of (b) Lyn, (c) Frk and (d) Hck genes were determined using real-time PCR, which demonstrated regulation of all three genes by the employed drugs (n = 3, *P < 0.001).