Fig. 2.

Membrane internalization stimulated by target cells is clathrin-dependent. a Effect of CPZ pretreatment on membrane internalization of NK cells stimulated by PEC. NK cells were pre-treated with 10 µg/ml of CPZ for 30 min and labeled with FM1-43FX (5 µg/ml) for 5 min and stimulated with PEC for 1 h. “−CPZ”: no CPZ pretreatment; “+CPZ”: CPZ pretreatment; “−PEC”: neither PEC stimulation nor PBS wash; “+PEC”: PEC stimulation and PBS wash. b, c Effect of CPZ pretreatment on FM1-43FX uptake of NK cells stimulated by PEC. The mean fluorescence intensities (MFI) showed the uptake of FM1-43FX. Black lines mean that NK cells were stimulated with PEC, and gray lines mean that NK cells were without PEC stimulation. The uptake of FM1-43FX in NK cells without CPZ pretreatment was defined to 100%. Relative uptake of FM1-43FX in CPZ pretreated NK cells was calculated by MFI (+CPZ)/MFI (−CPZ) × 100%. Error bar indicates SD. Scale bar is 10 µm. Data are representative of three independent experiments