Neuregulin-1β treatment induces phosphorylation of ErbB3 receptor in human cardiac fibroblasts. A, Western blot analysis of protein lysates of NHCV fibroblasts treated for 30 min with 30 ng/mL of NRG-1β. Bands shown are 185 kDa and were detected using an anti-rabbit antibodies that recognize phosphorylated ErbB3 (pErbB) at tyrosine position 1289 (Tyr1289) and pan ErbB3. B, Graphical representation shows densitometry analysis result for blot shown in A. C, Western blots of protein lysates of NHCV fibroblasts probed with pAKT at S473 or T308 and re-probed with pan AKT. Treatments shown (in triplicate) include untreated control cells, and cells treated with an ErbB3 blocking antibody (MAB3481), 30 ng/mL of NRG-1β (NRG), or both ErbB3Ab and NRG. Graphical representations of densitometry analysis results for the differentially expressed proteins are shown in C (n=3, *p < 0.05, ***p < 0.001 for NRG-1β-treated cells compared to untreated fibroblasts).