Study of cell-in-cell phenomena began with the desire to understand the complex phenotype, which stemmed from Lewis' observation of non-phagocytotic process of cell-eating-cell in 1925 1. Humble et al. coined the term “emperipolesis” (from the Greek, wandering round about within) in 1950s, to define the heterogeneous cell-in-cell phenomena when they studied biological interaction of lymphocytes with other cells 2. Emperipolesis has since been found to be commonly enacted by lymphocytes in physiological and pathophysiological settings 3. Since the term “emperipolesis” was annotated, a challenge has been set to understand how a cell inhabits in the other, what are their respective fates, and the biological relevance of co-habitation. Recently, Overholtzer et al. observed a homogeneous cell-in-cell phenomenon and named it as “entosis” (from the Greek, inside), an intercellular process that exhibits remarkable similarity to emperipolesis 4. Further investigation of this entotic process revealed that it requires the formation of adherens junctions in the absence of integrin signaling, and force-driven invasion of one cell into another cell. In addition, the process requires the Rho-ROCK signaling pathway of the invading cell and myosin-based contractile force from the recipient cell. Surprisingly, some invading cells chose to run away via a transcytosis-like movement while a small percentage of invading cells underwent cell division within the host cells.