  During the last decade, intracellular actin waves have attracted much
attention due to their essential role in various cellular functions, ranging
from motility to cytokinesis. Experimental methods have advanced significantly
and can capture the dynamics of actin waves over a large range of
spatio-temporal scales. However, the corresponding coarse-grained theory mostly
avoids the full complexity of this multi-scale phenomenon. In this perspective,
we focus on a minimal continuum model of activator-inhibitor type and highlight
the qualitative role of mass-conservation, which is typically overlooked.
Specifically, our interest is to connect between the mathematical mechanisms of
pattern formation in the presence of a large-scale mode, due to
mass-conservation, and distinct behaviors of actin waves.
