Figure 1. General Characteristics of Cell-in-cell processes.

In endocytic processes host cells internalize a target cell. Invasive processes are driven by activity of the internalized cells. “Cell types” refers to the host cells. Homotypic refers to the engulfing cell and the internalized cell being of the same cell type. Heterotypic means that the engulfing and internalized cell types are different. Emperipolesis historically involves survival of the internalized cell, but some authors extend its usage to cases wherein there may be death of the internalized cells. Cell-in-cell processes have been previously reviewed^13,17. Previous literature is available on cannibalism^18-20, phagoptosis²¹, phagocytosis¹² and emperipolesis²².