Pak1 and RAC1 inhibition phenocopies the effects of HDACIs on pMLC levels. (A) Western blot performed on Meg-01 cells treated for 24 hours with 10 μM of the PAK1 inhibitor WR PAK18 showing an increase in pMLC levels. The arrow indicates the corrected loading control. (B) Western blot performed on Meg-01 cells transduced with a constitutively activate (CA Rac1) or dominant-negative (DN Rac1) Rac1, showing a decrease and increase, respectively, in pMLC levels compared with empty vector (murine stem cell virus [MSCV]) alone.