FIG. 8.

Attenuation of neuregulin-1β (NRG)-activated phosphorylation of AKT and Erk1/2 by lapatinib (LPN) and trastuzumab (TZM). HiPSC-CMs were pretreated with lapatinib (1μM) or trastuzumab (1μM) for 30 min before changing to fresh media (vehicle control) or NRG 100 ng/ml (by adding 10X stock prepared in fresh media) for 30 min. Lysates were prepared and analyzed as described in the Materials and Methods section. (A) and (B) show representative traces of NIA analysis to illustrate the change of phosphorylated and non-phosphorylated peaks by NRG alone, or subsequently with LPN and TZM. (C) and (D) show quantification of AKT or Erk1/2 phosphorylation by the phospho-/non-phosphorylated peak intensity ratio, or by the peak intensity of all phosphorylated isoform peaks, respectively. Each bar represents the mean ± SE of three independent cell culture experiments. *p < 0.05 versus NRG treatment group. Isoelectric point (pI) is shown on the x-axis and chemiluminescence on the y-axis in (A) and (B).