Fig. 7. Model for MEX-5 asymmetry. Speculative model showing MEX-5 before (left) and after (right) asymmetry. MEX-5 is either bound (green) or unbound (blue) to cytoplasmic actomyosin, or to a component whose mobility is limited by actomyosin. Cortical contraction changes the localization, or dynamics, of actomyosin in the deep cytoplasm, such that MEX-5 concentrates in the anterior. Additional sharpening of the MEX-5 asymmetry might come from factors that modulate MEX-5 binding, such as phosphorylation by posterior-localized PAR-1 (red) or non-localized PAR-4 (not shown).