AIM To explore the components and the distributions of the cytoskeleton network in neoplastic Hep G2 cellsextracted with triton X-100 and (NH4)2SO4.METHODS Using the mouse lung adenocarcinoma cell sublines (C6/C7) with low and high metastasis as acontrol, the human hepatocellular carcinoma cell line (Hep G2) as well as the cell sublines (C6/C7) wasextracted with triton X-100 and/or (NH4)2SO4, then stained with Coomasie blue R250 or labeled withimmunoenzymatic technique to identify the cytokeratin-type or vimentin-type intermediate filamentcomponents and study the distributions of cytoskeleton comparatively.RESULTS Extracted with triton X-100 and/or (NH4)2SO4, then stained with Coomasie blue R250, the cells'cytoskeleton network were showed clearly; still it was very difficult to identify the variations of thecytoskeleton network in morphology by light microscopy when the same cells was extracted with the differentextraction above; compared with the low metastasis cells (C7), most of the high metastasis cells (C6) werelikely showed that the distribution of the cytoskeleton network was more irregular and uneven as well asgathering on one side to the cell neucleus, and so did a few of Hep G2 cells (the percentage of regular andeven distribution of cytoskeleton, C6: 8.0±1.0; C7: 84.0±2.0; Hep G2: 96.0±2.0; n = 500; x2-test,P<0.01). Moreover, extracted with triton X-100 and (NH4)2SO4, then labeled by immunoenzymatictechnique, the mouse lung adenocarcinoma sublines (C6/C7) were positive for cytokeratin antibody only, butthe hepatocellular carcinoma cell (Hep G2) was positive for both cytokeratin and vimentin antibodies.Besides these, in the same cells, the distribution of the intermediate filament network showed by theimmunoenzymatic technique was nearly keeping with that of the cytoskeleton network showed by Coomasieblue R250 stain.CONCLUSION ① It is very difficult to identify the variations of the cytoskeleton network in morphologyby light microscopy when the same cell was extracted with triton X-100 and/or (NH4)2SO4 then stained withCoomasie blue R250 in comparsion. ② The characterizing distribution of the intermediate filament as well asthe ctoskeleton network that was irregular, uneven and gathering on one side to the nucleus in neoplastic cellmight provide a valuable information for studing tumor metastasis. ③ In analysing the components ofintermediate filament protein of malignant tumor cells, the heterogenous proteins (co-expression) must betaken into consideration.