Fig. 2.

Calpain mediates TPE-induced collagen-I synthesis through the phosphatidylinositol 3-kinase (PI3K)/Akt/NF-κB signaling pathway. PMCs were incubated with TPE, MPE, or STB in the presence or absence of the calpain inhibitor MDL28170 (20 μM) for 24 h, after which protein levels of p-Akt, t-Akt, IκB-α, and collagen-I were measured using Western blots, and NF-κB activity was detected as described in materials and methods. A and C: representative immunoblots of p-Akt, t-Akt, and IκB-α. B: changes in relative density of p-Akt protein to t-Akt and GAPDH according to A (n = 5). D: changes in relative density of IκB-α protein to GAPDH according to C (n = 4). E: changes in relative NF-κB activity in PMCs (n = 4). Data are expressed as mean ± SE. *P < 0.05 vs. TPE.