Compromising Paks prevents CRTC1-Tax association and Tax recruitment to LTR. (A) RNAi depletion of endogenous Pak1 impedes the association of Tax with CRTC1. HeLa cells were transfected with the indicated expression plasmids and an siRNA against Pak1 (siPak1A). Interaction of Tax with CRTC1 was analyzed as in Figure 5. n.s.: non-specific protein reactive with anti-Pak1. (B) RNAi depletion of Pak1 and Pak3 perturbs the recruitment of Tax to HTLV-1 LTR. HeLa cells were firstly transfected with siGFP, siPak1 and siPak3. siGFP served as a negative control. After 24 h of siRNA transfection, cells were transfected with Tax expression plasmid and pLTR-Luc. Cells were harvested for ChIP assay using the indicated antibodies after another 48 h.