This latter view is also supported by the recently reported function of PAK1 in stimulation of colorectal proliferation by gastrins via multiple signalling pathways involving activation of ERK, AKT, and B catenin. Increased p21 activated kinase 1 expression product information is associated with invasive potential in uveal melanoma. Thus, it is conceivable to think that the contempor aneous shut down of either the RAF MEK ERK or PI3K AKT signaling pathway might at the basis of the susceptibility of HT29, A375MM and A549 cells to FTI and PAK inhibitors. All together our mammalian data substantially confirm the yeast data showing that PAK inhibition cooperates with FTIs in inhibiting proliferation of eukaryotic cells.

The susceptibility of the A549 lung cancer cell line, which harbours a K Ras mutation, to the combined use of IPA3 and FTI 277 is of particular interest, given the aggressiveness of current treatments for lung cancer. It has been previously shown Inhibitors,Modulators,Libraries that A549 cells treated with FTI 277 are blocked at the G2 M transition. Inter estingly, it was observed that antibodies developed against a specific C terminal Ste20 PAK homologue fa cilitates the release of Xenopus oocytes from G2 arrest. Given the observation that a combination of FTI 277 and IPA3 significantly increases the proportion of senescent A375MM cells, we propose that the combined effects Inhibitors,Modulators,Libraries of FTI 277 and PAK inhibitor IPA3 might simi larly release A549 cells from the FTI mediated G2 M block and promote senescence. To try to answer why the combinatorial use of IPA3 Inhibitors,Modulators,Libraries and FTI 277 does not re duce HeLa cell proliferation, we analysed the activation status and the intracellular localization of PAKs in HeLa and A375MM cell lines.

However, none of the parame ters measured correlated with the different effects that PAK inhibitors Inhibitors,Modulators,Libraries have on the respective proliferation abil ities. In HeLa cells the effects of FTI 277 on FA assem bly and vinculin recruitment are consistent with the anti proliferative function of FTIs and with the view that cytosolic PAK PIX GIT module activation is not in volved in the FTI mediated PAK activation response. Conclusions This work firmly establishes that PAK inactivation com bined with FTI treatment has a potent anti proliferative action on yeast as well as melanoma, colon and lung cancer cells. Further work will be required to elucidate how PAK inhibitors aid FTI anti proliferative action in these tumor cell lines.

Inhibitors,Modulators,Libraries Based on the yeast data, we suggest that ABC transporter recycling, consequent to FTI uptake, is the initial signal that activate PAK. Methods Yeast strains, plasmid constructs, media and growth conditions Strains Nutlin-3a side effects and oligonucleotides are listed in Tables 2 and 3, respectively. Media, yeast transformation and genetic manipulation as well as molecular procedures were as described previously.