Figure 4: Fluorescent E6BSA-FITC is trafficked in and out of the plasma membrane. (A, B) Frame-by-frame tracking (4 frames per sec) of E6BSA-FITC fluorescent puncta intensity and position revealed different types of fluorescent molecule movements. E6BSA-FITC puncta were mostly stationary (orange squares), however a few initially stationary fluorescent puncta (A; Type 1; blue diamonds) suddenly moved long distances along a directed path (also see Tracked Path inset) only to dim away gradually. (B) Other puncta (Type 2; magenta circles) rapidly appeared, moved randomly a short distance (also see Tracked Path inset) and then rapidly (~2.5 sec) disappeared. AFU: Arbitrary fluorescence units. Distance and speed of puncta movement is quantified in panels (C) and (D).