USP7 and ovarian neoplasm: Next, we tested the FP reagents in deconjugation assays by treating them with three human deubiquitylating enzymes (DUBs; UCH-L3, USP7/HAUSP and USP21), two viral ovarian tumour domain (OTU) DUBs and three SUMO-specific proteases (SENP1, SENP6 and SENP7).