FIGURE 8:

KalSec14-GFP disrupts receptor-mediated endocytosis in AtT-20 corticotrope tumor cells. (Left) Magnified 63× images showing Alexa Fluor 546–transferrin uptake (red) by AtT-20 corticotrope tumor cells expressing either GFP (top) or KalSec14-GFP (bottom). Cells were exposed to Alexa Fluor 546–Tf for 5 min at ∼24 h after transfection and were then fixed, stained, and imaged. Scale bars, 20 μm. (Right) Quantification of internalized 546-Tf. Data were collected using MetaMorph; values were normalized to cell size and relative to GFP control cells (n = 8 for GFP and 12 for Sec14-GFP; error bars, ± SEM; **p < 0.002). Results were confirmed in an independent experiment.