  Membrane tubulation is a ubiquitous process that occurs both at the plasma
membrane and on the membranes of intracellular organelles. These tubulation
events are known to be mediated by forces applied on the membrane either due to
motor proteins, by polymerization of the cytoskeleton, or due to the
interactions between membrane proteins binding onto the membrane. The numerous
experimental observations of tube formation have been amply supported by
mathematical modeling of the associated membrane mechanics and have provided
insights into the force-displacement relationships of membrane tubes. Recent
advances in quantitative biophysical measurements of membrane-protein
interactions and tubule formation have necessitated the need for advances in
modeling that will account for the interplay of multiple aspects of physics
that occur simultaneously. Here, we present a comprehensive review of
experimental observations of tubule formation and provide context from the
framework of continuum modeling. Finally, we explore the scope for future
research in this area with an emphasis on iterative modeling and experimental
measurements that will enable us to expand our mechanistic understanding of
tubulation processes in cells.
