It should be noted that almost all canonical concepts related to EGFR endocytic pathway regulation are based on studies of immortalized cells of tumor origin, such as HeLa, A431, A549, etc., expressing a high level of the receptor (according to estimates, more than 100,000–200,000 molecules per cell, as opposed to less than several thousand in normal cells), and, generally, no fundamental differences have been revealed. Here, EGFR is linked to neoplasm.