Although YFP-PARG is a soluble nuclear protein, a more demanding test of the utility of the GFP-nanobody RING was its ability to induce degradation of YFP-PML (promyelocytic leukemia) protein that is located in nuclear bodies and is stabilized in these bodies by a dense network of SUMO-SIM interactions (Shen et al., 2006). This evidence concerns the gene PML and acute promyelocytic leukemia.