Effects of EpiS-transfected MIC 216 cells on Caco2 cell colony morphology are preserved in Transwell filter cocultures. Fibroblasts were cultured for 3 days in the outer well of Transwell filters. Caco2 cells were then seeded and cultured for 10 days on the top of the inner well membrane (0.4 mm). (a) Caco2 on pCEN cells, (b) Caco2 on EpiS1 cells, and (c) Caco2 on EpiS2 cells. Magnification: ×250.