Fig. 5.

Analysis of JAK/STAT, MAPK and PI3K Activation by gp130. Panel A: Schematic representation of FLAG-tagged full length (Eg) and truncated (ΔB) gp130–EpoR fusion constructs showing the EpoR extracellular ligand binding domain (hatched), the membrane-spanning region and the cytoplasmic domain. Box 1 and Box 2 JAK binding domains are shown (shaded) and the phosphotyrosine residue docking sites for STATs are indicated. Panel B: Neonatal rat cardiomyocytes were transfected with pcDNA3.1, Eg and ΔB for 72 h in serum-free medium and subsequently stimulated with 100 ng/ml EPO for 30 min and harvested for Western Blot analysis. Blots were probed for Phospho-STAT 1 (Tyr⁷⁰¹)/Total STAT1; Phospho-STAT3 (Tyr⁷⁰⁵)/Total STAT3; Phospho-Erk1/2 (Thr²⁰²/Tyr²⁰⁴)/Total Erk1/2; Phospho-Akt (PKB: Ser⁴⁷³)/Total Akt(PKB).