Extracts derived from various medical mushrooms have been reported to have antitumor and immuno-modulatory properties. In order to investigate the antitumor activity of keumsa Linteusan, the water extract of Phellinus Iimteus, HT1080 cells, a human fibrosarcoma cell line, were treated with it and changes in cellular migration potential was tested in vitro. At a concentration range below 1,000 $mu$g/mL, Linteusan blocked, in a dose dependent manner, the migration of cells through Matrigel as well as Boyden chamber without affecting the viability of the cells. Prolonged treatment of HT1080 cells with Linteusan suppressed TNFa induced production of matrix metalloproteinase (MMP)-9 as well as basal level expression of MMP-2. Linteusan also affected the adhesion of the cells to fibronectin-coated surfaces. The effect of Linteusan on cell signaling pathways was also tested. Linteusan specifically affected TNF-$alpha$ induced phosphorylation of AKT in a dose-dependent manner, while phosphorylation levels of ERK remained unaffected. These data indicate that Linteusan blocks the migration of HT1080 cells by affecting various processes associated with cell migration such as the expression of matrix degradingenzymes,cell adhesion, and AKT-medicated cellular signaling pathways.