Cell culture medium and serum of mice harboring human medulloblastoma (MB) xenotransplants may contain EVs with encapsulated DNA corresponding to the amplified oncogenic c-Myc sequences (Balaj et al., 2011), while plasma of colorectal cancer patients was found to contain functional circulating DNA encoding mutant K-ras (Garcia-Olmo et al., 2010). Here, KRAS is linked to colorectal cancer.