We first observed that protein and mRNA levels of USP11, but not any other known PTEN DUBs (such as HAUSP, USP13, and OTUD3), were markedly lower in isogenic PTEN-null (PTEN-/-) HCT116 colon carcinoma cells compared to WT parent (PTEN+/+) or heterozygous (PTEN+/-) cells (Fig. 8a, b). This evidence concerns the gene USP13 and colon carcinoma.