Figure 2.

FHL2 induction by TGF‐β1 is dependent on intracellular Smad signalling. (A) TGF‐β receptor signalling is required for FHL2 induction. NRK‐52E cells were pre‐treated with activin receptor‐like kinase‐5 inhibitor SB431542 (10 μM), followed by incubation with TGF‐β1 (2 ng/ml) for 24 hrs. (B) Pharmacologic inhibition of different signal transduction pathways does not affect FHL2 induction by TGF‐β1. NRK‐52E cells were pre‐treated with either various chemical inhibitors or vehicle (Veh., 0.1% Me₂ SO) for 30 min., followed by incubating in the absence or presence of 2 ng/ml TGF‐β1 for 24 hrs. Wort., wortmannin (PI3K inhibitor) (10 nM); PD, PD98059 (MEK1 inhibitor) (10 μM); SB, SB202190 (p38 MAPK inhibitor) (20 μM); SP, SP600125 (JNK inhibitor) (20 μM). (C) Semiquantitative RT‐PCR analyses confirm overexpression of Smad7 in NRK‐52E cells. NRK‐52E cells were transiently transfected with Smad7 expression vector (pSmad7) or empty vector (pcDNA3). (D) Western blot shows that overexpression of Smad7 suppressed FHL2 induction by TGF‐β1.