Fig. 6

Mitogen-activated protein kinase kinase kinase 1 (MEKK1) mediates CXCL12-stimulated c-Jun N-terminal kinase (JNK) phosphorylation and SMAD3 phosphorylation in WI-38 cells. a After transfected with control siRNA (Con siRNA 100 nM) or MEKK1 siRNA (100 nM) for 24 h, the WI-38 cells were exposed to CXCL12 (10 ng/ml) for additional 10 min. Protein levels of phospho-JNK T183/Y185 or JNK in cell lysates were determined by western blot. Statistics are showed as the mean ± S.E.M. of three separate experiments. * p < 0.05, compared with CXCL12 treatment without MEKK1 siRNA. b After transfected with control siRNA (Con siRNA 100 nM) or MEKK1 siRNA (100 nM) for 24 h, the WI-38 cells were exposed to CXCL12 (10 ng/ml) for additional 20 min. Protein levels of phospho-SMAD3 Ser208 or α-tubulin in cell lysates were determined by western blot. Statistics are showed as the mean ± S.E.M. of three separate experiments. * p < 0.05, compared with CXCL12 treatment without MEKK1 siRNA