SMURF1 is another member of the NEDD4 subfamily that acts to negatively regulate p53 activity during breast (40), ovarian (46), gastric (42), and glioblastoma (166) tumorigenesis by augmenting the ubiquitylation activity of MDM2 – a RING E3 ligase that specifically targets p53 for proteasomal degradation (76, 158, 167, 168). The gene discussed is TP53; the disease is glioblastoma.