Endosomes Move along Microtubules

<div><p>(A) Confocal microscopy of a Vero cell transfected with GFP-Rab5 and RFP-Rab7 after treatment with 5 μM nocodazole. Endosomes are enlarged and many (approximately 75%) Rab5-positive endosomes are also positive for Rab7 (arrowheads). Scale bar represents 10 μm.</p> <p>(B) Cells treated as in (A) were incubated with SFV-Cy5, and fixed 1 h after warming. SFV-Cy5 is present in bigger endosomes positive for Rab5 and Rab7 (arrowheads). Scale bar represents 5 μm.</p> <p>(C) Confocal microscopy of a Vero cell treated with 5 μM nocodazole and incubated with SFV-Cy5. After 1 h of internalization at 37 °C, cells were fixed, permeabilized, and immunostained for EEA1 and Rab7. Endosomes positive for both markers can be seen (white rectangles) (41%), and SFV-Cy5 is captured in these structures (yellow rectangles). The protrusions of Rab5 shown in (A) are not seen in (C) and are probably caused by overexpression of the Rab proteins. Scale bar represents 10 μm.</p>