PTEN and neoplasm: Monoubiquitylation of these sites is important for regulation of PTEN-mediated tumour suppression and its nuclear import.22 The major DUB responsible for PTEN deubiquitylation is USP7/HAUSP.23 Based on the peptide sequences surrounding Lys13 and Lys289, we designed two FP reagents that comprised a TAMRA-labelled 17-amino-acid PTEN peptide (i.e., PTEN[5–-21] and PTEN[281-–297], respectively).