A central objective of my research is to determine how macromolecular crowding and liquid-liquid phase separation (LLPS), which characterizes the cytoplasmic milieu of living cells, affects cellular response to osmotic stress. My research strategy is to develop and deploy a carefully selected set of well-characterized vesicular model systems, which recapitulate the essential physical features of living cells including femtoliter scale compartmentalization of the aqueous phase; molecular crowding and phase separation within the cellular interior; and compositionally diverse, and structurally elastic, membrane boundary. These models will then be used to generate quantitative relationships, which map (1) the model protocells that reconstitute “macromolecular crowding” inside; (2) mesoscale shape transitions in ATPS-encapsulating giant vesicles subject to osmotic gradients; and (3) the compositional dependence (i.e., domain formation) of ATPS-encapsulating giant vesicles. Building on the experimental model system developed by Keating (PNAS, 2005), Dimova, and Lipowsky (Soft Mattter, 2012), we reconstitute minimal crowding and conditions for dynamic microcompartmentation inside cell-sized giant vesicles which help us on studying the biophysical features on living cell.