Inhibition of TGF-β receptor prevents calpain-2-induced increases in the levels of P-Akt-S473 and P-Akt-T308. PASMCs were transfected with plasmids containing human calpain-2 gene or empty plasmids and then incubated with and without SB431542 (10 μM) for 24 h, after which P-Akt-S473, P-Akt-T308, and total Akt were measured by Western blot. A: representative immunoblots of P-Akt-S473, P-Akt-T308, and total Akt. B: bar graph showing the changes in protein levels of P-Akt-S473 and P-Akt-T308. Values are means ± SE; n = 5. *P < 0.05 vs. empty vector in vehicle. **P < 0.05 vs. empty vector in SB431542. #P < 0.05 vs. calpain-2 vector in vehicle.