MDM2 and cancer: Recent studies have emerged to reveal the potential role of NEDD4 in human cancer by modulating ubiquitination‐dependent degradation of downstream substrates involved in carcinogenesis and tumorigenesis including IGF‐IR, FGFR1, EGFR, VEGFR2, HER3/Erb3, PTEN, Notch, phosphor‐Akt, c‐Myc, Ras, and mdm2.14, 15