The predicted interaction of MB21D2 with Mab21‐nucleotidyltransferase enzymes (Fig. S11B), such as cGAS, and mitochondrial regulator, such as MIEF proteins (Fig. S11B) [27, 28], may further explain the clonal selection event, as fittest clone selection was previously observed in many cancers such as multiple myeloma [47]. Here, MB21D2 is linked to plasma cell myeloma.