Fig. 3. Pak kinase is required for polarization of protrusions but not Golgi reorientation. (A) Pak kinase activity controls the spatial localization of protrusions. Representative cells injected with pEGFP-F (membrane) along with a control plasmid, pRFP::Pak1 K299A (Pak KD), or pRFP::Pak1 AID (PakAID). Expression of constructs was confirmed by immunofluorescence (not shown). Protrusions are found at the front (open arrows) in control cells, but are delocalised in cells in which Pak is inhibited (filled arrows). None of the constructs inhibit Golgi reorientation (asterisk). (B) The effects of various constructs on Golgi reorientation (black bars) or protrusion polarization (white bars). Error bars represent standard deviation. Asterisks mark highly significant (***P<0.0001) differences compared with control. (C) The delocalized protrusions, induced after Pak inhibition are dependent on Rac. Representative cell injected with pEGFP-F (Membrane), pRFP::Pak1 AID and pRK5-MYC::RacN17. Bars, 20 µm.