Actin Gelation and the Structure of Cortical Cytoplasm

In the past 5 years we have seen the revival of an old idea: that transformations between "sol" and "gel" states of protein might be important for the cytoplasmic structure and movement of peripheral cytoplasm in many eukaryote cells (Frey-Wyssling 1957). This revival arose from the appreciation that the cortical cytoplasm of many cells contains numerous actin filaments and that extracts containing actin from broken cells could be induced to solidify or remain liquid, depending on the experimental conditions (for review, see Taylor and Condeelis 1979).