Fig. 4. TGF-β1 induces EMT in MTEC in a JNK1-dependent, but JNK2-independent, manner. (A) TGF-β1-induced loss of TER, indicative of barrier disruption, in wild-type MTEC is abrogated in MTEC lacking JNK1^–/–, but not in JNK2^–/– MTEC. Cells were exposed to 5 ng/ml TGF-β1 every other day for the indicated days of culture. Data are graphed as percentage change in TER from baseline, as recorded over a time period of 10 days. Results represent three independent experiments. Absolute TER readings (Ohms x cm²) before initiation of TGF-β1 exposure were: wild type 1143.3±149.2; JNK1^–/– 3521.7±161.4; JNK2^–/– 2956.7±150.5 (n=6/group). (B) Comparative evaluation of -SMA expression in wild-type, JNK1^–/– and JNK2^–/– MTEC, exposed to TGF-β1 (10 ng/ml, every other day for 8 days). -SMA expression (Red) was detected by immunofluorescence. Green, Nuclear counterstain, Sytox). The percentage of -SMA expressing cells was quantified by counting the number of positive cells per field (n>50 cells). (C) Confirmation of genotypes of JNK1^–/– or JNK2^–/– MTEC by western blot analysis of total JNK.