Figure 1.

Schematic diagram of hereditary differences between chromosome and ecDNA. When the oncogene is on a chromosome, the sister chromatids attached to the centromeres are equally divided into two daughter cells because of the pull of spindle fibers during mitosis, this is a classic Mendel’s law. But when the oncogene is located on ecDNA, the ecDNA replicates with the chromosome, the spindle fibers can’t hold on to it because there is no centromere, which leads to the ecDNAs after replication being randomly divided into two daughter cells during cell cleavage.