Lamins are the major components of the nuclear lamina which underlies the nuclear envelope of eukaryotic cells , they are members of the intermediate filament protein family. Vertebrate lamins are classified into 2 types, A and B. Lamin B is expressed in all kinds of cells. It is a component of the interphase nuclear lamina, is required to maintain nuclear shape and mechanical integrity. Lamin B has a role in spindle assembly. Furthermore, lamin B was essential for the formation of the mitotic matrix that tethers a number of spindle assembly factors.