Confluent biological tissues can be thought of as active multicellular systems: they consume energy to generate motion or change their conformation. This activity affects the cohesion and the organization of the tissue, and is at the origin of large collective motions, such as those observed during morphogenetic movements. From a macroscopic perspective, this activity allows the tissue to shift from a solid-like to a fluid-like state. Yet, biological cells are much more complex than punctual or colloidal particles: they can deform, proliferate, communicate, and adapt in ways that cannot be modelled with simple active particles. Moreover, because of their high deformability/low compressibility features, their mechanical interactions in a tissue are non-pairwise. An essential property for the correct functioning and integrity of tissues is their capacity to maintain sharp boundaries, in spite of the noise induced by the cell renewal and cell activity. Depending on the physical and biological properties of the two cell population, the boundary can destabilize through various mechanisms. In particular, we have shown in a recent study that the intrinsic stochastically of cell division and cell death (apoptosis) induces a temporal instability of the mean position of the boundary. Using both numerical and modelling techniques, we propose to explore the “phase space” of the boundary between two cell populations and determine the domains in which the boundary destabilizes.