Definition: The mechanisms by which a cell becomes internalized in another. The host cell may engulf another as do PHAGOCYTIC CELLS, or the host cell may be invaded by another cell (ENTOSIS), or internalization processes may involve the cooperation of both the host cell and the cell being internalized. Viable cells may remain in non-phagocytic cells (EMPERIPOLESIS), undergo cell division, pass through and then out of the host cell (TRANSCELLULAR CELL MIGRATION), or trigger APOPTOSIS of the invaded cell.
