Epitheli a l mesenchymal interaction(EMl) is well known to be essential in eznbryonic deve]opment. wound hea]jng a nd ca rci nogenes is. Th is study was a i med to design in vi tro model for the investigation of protein analysis in epithe li al a ncl mesenchyma l i nteract ion(EMI) . This stucly usecl oral squamous cell carcinoma cell line(YD-lOB) . 1'0 investigate the clifference 0 1' protei n ex press ion of cancel‘ cells influencecl by variable in vitro conditions. three different models were des ig necl ; Collagen gel- basecl ca ncer cell culture model devoid of fibroblasts(C) , Direct coτulture moclel(M2) composed of ca ncer cells beneath co ll agen gel embeclded with Swiss 31'3 fibroblasts ‘ and Indi rect co-culture model(Ml) with collagen layer betwecn cancel‘ cells and collagen gel with f lbroblasts Two-dimensional electrophoresis was performed to compa re t he diffe r ence of protein express ion pattern of ca ncer cells aznong three znodel systems. Protein identification was done by MALDI-TOF. As res ults ‘ pl'O te in express ion pat tem of cancel' cells was quite different between znonolayer cul ture and coll agen gel based cultu re. Aclditiona ll y. protein expression was different between culture models with fi broblasts and without fibroblasts a ncl between ind irect contact and direct contact of two cell types ‘ Among differentia l prot ei n spots. catheps in D WäS iuenLifï ed by MALDl• TOF Cathepsin D exprcssion was increased from C model to 11띠 and M2 model by West em blott ing. suggest ing that cathe psi n D expression may be activated by direct and indirect stimulation of stromal fï broblas ts F' rom these resul ts ‘ these models could be appropriate for EMI study and cathepsin D mi ght be incluced by fi broblasts s timulation