For instance, single ubiquitination to Lys13 and Lys 289 of the PTEN protein presenting in a loop regulates PTEN nuclear import and stability by monoubiquitination and tumor suppression by polyubiquitination; the loop is formed by the interaction between the C-terminal tail and C2 domains of PTEN (70, 71). The gene discussed is PTEN; the disease is neoplasm.