Effect of MKK4 on uPA expression levels, as well as the migration and invasion SK-Hep-1 cells.
(A) Cells were treated with various concentrations (0, 5, 10, and 20 µM) of LicA for 24 h, and then cell lysates were subjected to SDS-PAGE followed by Western blotting with anti-p-MKK3/6, anti-MKK3/6, anti-p-MKK4, and anti-MKK4 antibodies. β-actin was used as an internal control. (B) Cells were treated with si-MKK4 (200 nM), and its inhibitory potency toward MKK4 or MKK3/6 was analyzed with Western blotting. (C) SK-Hep-1 cells were pretreated with si-MKK4 (200 nM) for 24 h and incubated in the presence or absence of LicA (10 µM) for another 24 h. Cell lysates were then subjected to western blotting to determine the protein expression levels of uPA. Cells were also assessed for migration (D) and invasion (E). *p<0.05, untreated cells versus si-MKK4 or LicA; # p<0.01, LicA versus si-MKK4 plus LicA.