NPs colocalize with wildtype Rab5-GFP and mutant Rab5-Q79L-GFP (A, B) Fluorescent micrographs of L-Cells expressing wildtype (A) and mutant (B) Rab5-GFP that have been incubated with dual-fluorescently-labeled RGD-tagged NPs for 60 min at 4°C followed by 60 min at 37° C. (C) A cropped region from (A) showing a NP lacking GFP colocalization (i), and 2 NPs colocalized with GFP-Rab5 (ii, iii). (D) Intensity profile of dashed line in (C). (E) Average number of NPs colocalized and not colocalized with GFP-Rab5 at 60 min of 37°C incubation (n = 20 cells). (F) Cropped region from (B) showing giant early endosomes containing individual, resolvable nanoparticles (arrows). Scale bars in (A, B) and (F) are 10 and 5 μm, respectively. Adapted and reprinted with permission from (53); copyright Elsevier.