English: Schematic representation of membrane-less organelles (MLOs). Eukaryotic cells contain different MLOs formed by liquid–liquid phase separation. (A) Representation of liquid–liquid phase separation. In order to promote interaction between macromolecules and to obtain a chemical equilibrium, high energy is required with a correspondent reduction of entropy. In this condition, proteins (in blue) and RNA (in red) are prone to undergo liquid–liquid phase separation. In particular, the increase in energy and the reduction in entropy lead to a decrease in macromolecule solubility and an increase in protein-RNA interactions. The result is a higher concentrated phase, that promotes the formation of membrane-less organelles (MLOs). (B) Representation of membrane-less organelles (MLOs). The MLOs form sub-compartments both in the nucleus and in the cytoplasm. Nucleus is characterized by the presence of nucleoli (in red) that are involved in the ribosome biogenesis; paraspeckles (in purple), whose formation is promoted by the lncRNA NEAT1, that interacts with several RBPs, including FUS, in the core, and TDP-43 in the shell; Cajal bodies (in green) that are involved in the snRNP biogenesis; and super-enhancers (in yellow) that are clusters of master transcription factors and transcriptional co-activators involved in gene expression. In the cytoplasm, eukaryotic cells harbor P-bodies (in blue), involved in the control of mRNA translation and mRNA storage, and stress granules (in orange) whose formation, upon stress condition, requires the interaction between RNA (in grey) and proteins.^[1]