Erythrocyte spectrin and nonerythroid spectrin (fodrin, calspectin) are major constituents of the membrane cytoskeleton, forming a two-dimensional meshwork beneath the outer cell membrane ( 1 , 2 ). The three-dimensional organization of the membrane cytoskeleton has been extensively studied in the erythrocyte, providing a model shown in (Fig.1 ) ( 1 ). Spectrin and fodrin are rod-shaped proteins and consist of α and β subunits (several isoforms exist) ( 1 ). Fig. 1.  Schematic representation of the organization of spectrin cytoskeleton of erythrocyte.