A sphere is the lowest energy configuration for bound system (like a bubble). Other cell shapes require focal adhesion on the outside of the cell or asymmetrically organized structures like actin filaments on the inside of the cell. Cells often temporarily "abandon" the production of some adhesive and structural proteins when changing states to redirect energy to the new process and allow for some reorganization.
Cell-cell signaling (internal and external signal transduction pathways) molecules that inducing via cell surface adhesion molecules have main role in spherical shape of cells.
A sphere is the lowest energy configuration for bound system (like a bubble). Other cell shapes require focal adhesion on the outside of the cell or asymmetrically organized structures like actin filaments on the inside of the cell. Cells often temporarily "abandon" the production of some adhesive and structural proteins when changing states to redirect energy to the new process and allow for some reorganization.