Actin Accumulation in Mutant Cells
(Actin filaments are depicted in florescent red.) During cell division in normal cells, a protein called cyclin-dependent kinase 1, or Cdk1, triggers a chain of events that causes actin filaments to assemble at the cell surface. But Cdk1 also takes measures to prevent excess actin from building up. In mutant cells (second from the right) where Cdk1 cannot perform this function, actin accumulates unchecked and prevents proper cell division.