Figure 4.
Neuregulin (NRG) induces the intranuclear colocalization of ErbB4 and Stat5a. Full-length ErbB4 (HER4) (green) localizes to the membrane when expressed in ErbB4-naive Gestational Day 17.5 Type II cells isolated from HER4heart (−/−) lungs. Stat5a (red) localizes diffusely in the cytoplasm and nucleus. (A) Twenty-four–hour exposure to mature, NRG-containing, fibroblast-conditioned medium (FCM, right) induces the localization of ErbB4 to the nucleus and colocalization with Stat5a. (B) The prevention of nuclear localization, using the mutant ErbB4 (HER4 muNLS), leads to a more diffuse localization of Stat5a in the cytoplasm, and prevents FCM-induced colocalization with Stat5a. Nuclear localization is confirmed by 4′,6-diamidino-2-phenylindole (DAPI) staining (blue).