NMuMG and MCT cells underwent transforming growth factor (TGF)-β1-mediated epithelial to mesenchymal transition. Phase contrast images of (a,e) NMuMG and (i,m) MCT cells with (TGF-β1) and without (control) TGF-β1 treatment (5 ng/ml) for 48 hours. Immunofluorescence detection of (b,f,j,n) E-cadherin, (c,g,k,o) zonula occludens (ZO)-1, and (d,h,l,p) F-actin in NMuMG and MCT cells treated with 5 ng/ml TGF-β1 (TGF-β1) or without TGF-β1 (control) for 48 hours. TGF-β1 induced cell elongation, loss of cortical actin and junctional E-cadherin and ZO-1 staining, and formation of actin stress fibers in NMuMG and MCT cells. Micrographs are representative of at least three independent experiments.