Only 3.9% (14/356) of discordant mutations found in xenografted liver metastases affected cancer-associated genes, including a third hit to APC, which was already biallelically inactivated in Patient #1 samples, and MEGF6 mutation in Patient #2 (Fig. 3b, c, Additional file 2: Table S1E). Here, MEGF6 is linked to cancer.