However, the unique phenotypes associated with PAK6 deletion imply that additional specific PAK6 substrates remain to be discovered. The mode of regulation of PAK6 is thought to be similar to that previously identified for PAK4, but this has not been shown with a cognate PAK6 sequence. Furthermore, the impact of somatic, acquired cancer mutations in PAK6 has not been studied, and structural biology techniques to identify potential ways to specifically target dysregulated type II PAKs have not yet 
been successful. In this study we have addressed each of these specific questions regarding PAK6 signaling. We have conducted an investigation into the substrate specificity of PAK6. We find that PAK6 has an identical consensus phosphorylation site sequence to PAK4 and PAK5. While PAK5 and PAK6 appear to be partially redundant, they are thought to have functions distinct from PAK4. Given that these three kinases share the same phosphorylation consensus, it seems likely that targeting of specific downstream substrates involves interactions outside of the kinase active site, perhaps mediated by accessory proteins. As noted previously, the PAK5/PAK6 phosphorylation site in PACSIN1 conforms well to the type II PAK consensus sequence, having an Arg residue at the P-2 position, a Val residue at the P +1 position, and a Ser phosphoacceptor residue. By contrast, the sequence surrounding the PAK6 phosphorylation site in androgen receptor does not conform to the consensus, suggesting a role for non-active site interactions in directing phosphorylation of androgen receptor. The general type II PAK consensus is overall similar to the type I PAK consensus sequence as determined for PAK1 and PAK2. However, phosphorylation of PACSIN1 specifically by type II PAKs can be explained by phosphorylation site recognition by the kinase catalytic domain. These observations suggest that differences between type I and type II PAKs in their preferred phosphorylation site sequences are important for specific substrate targeting in vivo. We discovered that PAK6 is inhibited by its pseudosubstrate sequence. Our previous studies had shown that PAK6 could be inhibited by the PAK4 pseudosubstrate sequence, so our current study builds on our previous finding to show that the PAK6 pseudosubstrate sequence can inhibit its own kinase activity. We also find that a melanoma-associated mutation within the pseudosubstrate sequence, P52L, disrupts PAK6 autoinhibition enhancing its kinase activity, potentially correlating with increased expression of PAK6 in prostate cancer, and implied alterations in kinase activity. Establishing that this mutation impacts pseudosubstrate autoinhibition may facilitate future PAK6 studies. Finally, we determined two co-crystal structures of PAK6 in complex with ATP-competitive small molecule inhibitors. These co-crystal structures will facilitate an improved understanding of the modes of targeted inhibition for type II PAKs, and may aid future studies that aim to design inhibitors specific to each of the type II PAK family members. In sum, the current study provides significant advances in the understanding of the type II PAK family member, PAK6, and will facilitate future studies into PAK signaling and targeted drug development. With the global pandemic of diabetes affecting every continent, the impact of diabetic micro- and macro-vascular complications is far reaching. Central to all vascular complications is endothelial dysfunction. However, equally significant is the inability to repair dysfunctional endothelium. The process of repair is mediated largely by vascular progenitor populations. One such progenitor population, CD34+ cells are hematopoietic cells which Fingolimod Src-bcr-Abl inhibitor exhibit altered in vitro and in vivo function in individuals with vascular complications. CD34+ cells represent an ideal biomarker for the prediction of the cardiovascular disease, metabolic syndrome and type 2 diabetes. CD34+ cells function to provide paracrine support to AZ 960 905586-69-8 injured vasculature and tissues. Their reparative function has broad implications for supporting the health of an individual, and this has led to the use of these cells in clinical trials for treating ischemic conditions. Transient downregulation and functional inhibition of the intracellular TGF-��1 pathway in diabetic human CD34+ cells corrects key aspects of their dysfunctional behavior and this likely occurs through effects on critical TGF-��1 target genes. To this end, recent data confirms the role of one such TGF-��1-regulated gene, PAI-1, as an important mediator of cellular growth arrest.