Figure 5. Angiotensin II (Ang II) induced biphasic extracellular signal‐regulated kinases 1 and 2 (ERK1/2) activation, with the second activation dependent on interleukin 11 (IL‐11).

A, Adventitial fibroblasts (AFs) were exposed to Ang II (10⁻⁶ mol/L) for indicated time, and the protein level of phosphorylated ERK1/2 (p‐ERK1/2) was measured by Western blotting. B, AFs were pretreated with PBS or IL‐11 neutralizing antibody 1 hour before Ang II (10⁻⁶ mol/L) treatment. Then, AFs were exposed to Ang II or PBS for indicated time. The level of p‐ERK1/2 (1.00‐, 3.14‐, 2.25‐, 0.76‐, 2.74‐, and 0.73‐fold) was measured by Western blotting. N=4. C, AFs were transfected with control small interfering RNA (siRNA; siCON) or Krüppel‐like factor 15 (KLF15) siRNA (siKLF15) for 48 hours. AFs were pretreated by IL‐11 neutralizing antibody 1 hour before they were stimulated by Ang II for 5 minutes (1.00‐, 3.52‐, 4,04‐, 0.88‐, 3.76‐, and 3.57‐fold) or 4 hours (1.00‐, 2.31‐, 1.42‐, 1.08‐, 3.90‐, and 1.46‐fold). p‐ERK1/2 expression was measured by Western blotting. N=4. D, AFs were incubated with ERK1/2 signaling inhibitor (ERKi) 1 hour before or after Ang II 24‐hour stimulation. The protein levels of IL‐11 (1.00‐, 1.41‐, 0.96‐, and 1.26‐fold), KLF15 (1.00‐, 0.62‐, 1.08‐, and 0.49‐fold), collagen, type I, α 1 (COL1a1) (1.00‐, 1.69‐, 0.80‐, and 0.92‐fold), and α‐smooth muscle actin (ACTA2) (1.00‐, 1.53‐, 0.95‐, 0.92‐, and 0.49‐fold) were measured by Western blotting. The right panel was the quantity of the Western blot. N=4. CON indicates control. *P< 0.05, **P< 0.01, and ***P< 0.001.