Fig. 6. Multiple knock down of Rho GTPases revealed a role for Rac1, but not RhoA, in MMP-1 overexpression following Cdc42 silencing. HSFs were transfected with the indicated siRNAs at a concentration of 10 nM. To reach the same final concentration of 30 nM siRNA in each condition, transfection mix were supplemented with the irrelevant siScr siRNA. Representative western-blot analysis of whole-cell lysates 72 hours after transfection (cell lysates) and of serum-free medium conditioned for 16 hours between days 2 and 3 after transfection. Cell lysates and conditioned medium (C.M.) were analysed by immunoblotting with specific antibodies to RhoA, Rac1, Cdc42, ERK1/2 and MMP-1. (bottom) Densitometric analysis of MMP-1 measurements by western-blot analysis of C.M. Results are expressed as the means±s.d. of three independent experiments. The concentrations of the siRNA in the table below the figures are in nM.