It is well established that inhibition of the proteasome or DUBs causes accumulation of ubiquitinated proteins.36 Like what we previously reported with other cancer cells,35 PtPT dose- and time-dependently induced marked increases in both ubiquitinated proteins (Ubs) and proteasome substrate protein p27 in all the CML cell lines we tested (Figure1a). Here, PTPN2 is linked to cancer.