Transforming growth factor (TGF)-β1 induced spindle-shaped morphology in nontransformed human mammary epithelial cells (HMECs) and human epidermal keratinocytes (HEKs). Phase contrast images of (a,e) HEK and (i,m) HMEC cells with (TGF-β1) and without (control) TGF-β1 treatment (5 ng/ml) for 48 hours. Immuno-fluorescence detection of (b,f,j,n) E-cadherin, (c,g,k,o) zonula occludens (ZO)-1, and (d,h,l,p) F-actin in HEK and HMEC cells treated with 5 ng/ml TGF-β1 (TGF-β1) or without TGF-β1 (control) for 48 hours. TGF-β1 induced cell elongation and formation of actin stress fibers in the HEK and HMEC cells. However, junctional E-cadherin staining remained intact after TGF-β1 treatment. ZO-1 was not detected in the HEK cells and little was observed in the HMEC cells with or without TGF-β1 treatment. Micrographs are representative of at least three independent experiments.