PAK1 and neoplasm: Notably, this in vivo tumor-promoting effects of PAK1 in myxofibrosarcoma was effectively negated upon transduction with siCSF2 in the PAK1-transfected mice, even to the degree indistinguishable from that of the empty control/siCtrl group, as evidenced by gross examination of excised xenografts (Figure-S8A-B).