For example, U2 Small Nuclear RNA Auxiliary Factor 1 (U2AF1), a spliceosome gene related to cancers and myelodysplastic syndrome52,53, has no evidence of PPI with any co-opted E3 ligase but interacts with SMURF1, which may serve as a novel E3 ligase in PROTAC (Fig. 5b). This evidence concerns the gene SMURF1 and cancer.