The invention discloses application of ELL as an E3
ubiquitin ligase. The application of ELL
protein or
truncated protein of the ELL
protein to at least one of 1-6: 1, a
protein product for degrading c-Myc is prepared; 2, the ELL protein or the
truncated protein of the ELL protein is used as the E3
ubiquitin ligase; 3, a product for inhibiting tumor
cell proliferation is prepared; 4, a product for inhibiting tumorigenesis is prepared; 5, a product for identifying or assisting in identifying whether tissue to be detected is
tumor tissue or not is prepared; 6, a product for identifying or assisting in identifying whether a patient to be detected is a
tumor patient or not is prepared. The experiment proves that ELL is combined with c-Myc and induces c-Myc to be degraded through
proteasome, in-vivo and in-vitro studies both indicate that the ELL has the characteristic of the E3
ubiquitin ligase, can inhibit tumor
cell proliferation and tumorigenesis, can be used as a
molecular marker for tumor
clinical diagnosis, and can be used for preparing the
medicine or a kit for inhibiting tumors and a kit for diagnosing the tumors as the novel E3
ubiquitin ligase of c-Myc.