EGF and neoplasm: Two tumor-derived cell lines, HeLa and A549, which are widely used in endocytosis studies, demonstrated canonical type of EGF-receptor endocytosis with fast delivery of the bulk internalized EGF-QDs into EEA1-positive early endosomes, albeit with some variability in the dynamics (Figure 3), which may be explained with a particular Rab5 isoform, which functions predominantly in a cell line [61].