Before revision:  We exemplify our findings based on a model of intracellular actin waves . As biological cells are inherently mass-conserved systems, our results provide a key concept to understand the ubiquitous occurrence of actin waves in cells, explaining why they are so common, and why their dynamics is robust and long-lived.
After revision:  We exemplify our findings based on a model of intracellular actin waves since, on time scales of wave propagations over the cell scale, cells obey the conservation of actin monomers. The results provide a key concept to understand the ubiquitous occurrence of actin waves in cells, explaining why they are so common, and why their dynamics is robust and long-lived.