Fig. 9. Surface tTG contributes to TGFß-dependent increase in Fn assembly by WI-38 fibroblasts. (A,B) 42 kDa Fn fragment and anti-tTG antibody inhibit TGFß-stimulated increase of [¹²⁵I]Fn incorporation into the deoxycholate-insoluble fraction. (A) Deoxycholate-insoluble [¹²⁵I]Fn in the matrix of cells grown for 36 hours with or without TGFß in the presence of 50 nM [¹²⁵I]Fn was analyzed by reducing SDS-PAGE and autoradiography. (B) Quantitation of incorporation of [¹²⁵I]Fn into the deoxycholate-insoluble fraction. ¹²⁵I-labeled bands corresponding to Fn monomer and polymer were cut out of the gels and counted. The results are representative of three independent experiments (mean±s.e.m.). (C) TGFß-mediated enhancement of Fn fibril formation is inhibited by the 42 kDa Fn fragment and anti-tTG antibody. Cells grown for 36 hours with 50 nM exogenous Fn and either 2 µM 42 kDa fragment, 20 µg/ml anti-tTG antibody or without these treatments were stained with anti-Fn antibody. Bar, 50 µm. (A-C) Where indicated, cells were grown with 20 µg/ml anti-tTG antibody, blocking anti-5ß1 integrin mAb BMA5, control nonimmune IgG or 2 µM 42 kDa or 110 kDa Fn fragments.