Abstract: | A strain-specific antimitotic substance is present in large mononucleate amoebae. It inhibits mitosis when injected into amoebae of heterologous strains. The antimitotic substance has been isolated from homogenized cells, and some of its properties have been studied. The results obtained show that the active factor is a protein(s) of molecular weight between 200,000 and one million. The activity of this substance differs from other known antimitotic agents in that its action is strain-specific. |