Fig. 1. Subcellular localization of the ErbB family members. (A) CHO cells expressing EGFR-CFP, ErbB2-YFP, ErbB3-CFP or ErbB4-JMa-GFP were serum-starved for 24 hours at 37°C, and then observed by confocal microscopy. Note that the FP-fused EGFR, ErbB2 and ErbB4-JMa were localized in the plasma membrane, whereas ErbB3-CFP was mainly in the nucleus. (B) CHO cells co-expressing EGFR-YFP and ErbB3-CFP, ErbB2-YFP and ErbB3-CFP, or ErbB4-JMa-YFP and ErbB3-CFP were serum-starved, and then observed by confocal microscopy. Note that a large fraction of ErbB3-CFP was localized in the plasma membrane when co-expressed with EGFR-YFP or ErbB2-YFP. By contrast, the majority of the ErbB4-JMa-YFP protein was localized in the nucleus when co-expressed with ErbB3-CFP. Bars, 10 µm.