Label-free imaging of epidermal growth factor receptor-induced response in single living cells.

Epidermal growth factor receptor (EGFR), which belongs to the second-largest protein family for cell signal transduction, plays crucial roles in homeostasis, cellular organized patterns and most human cancers. In EGFR-activated signaling networks, the detection of the spatial and temporal dynamics of cascades that encode the many cell fates is still a challenge. Here, we report real-time imaging of epidermal growth factor (EGF)-induced EGFR activation and its signaling cascade in single A431 cells using surface plasmon resonance (SPR) microscopy. A two-phase SPR response pattern was observed within 30 min after EGF treatment, including a positive SPR response that was related to the EGFR-activated mass redistribution in the first 600 s, and a subsequent negative SPR signal caused by the morphological change of the cells. Furthermore, the inhibitor analysis verified that AG1478 inhibited the response from the whole the cell, whereas cytochalasin B strongly inhibited the response from the cell edge region.