Recombination signal-binding protein J (RBPJ) is a crucial downstream effector of Notch signaling, which is involved in cell proliferation, differentiation, and apoptosis. It plays an important role in tumorigenesis although the further studies and concrete evidence are still needed. Especially for endometrial carcinoma, the functions and mechanism of RBPJ are still elusive. Previous study demonstrated that RBPJ repressed expression of miR-155 by binding to its promoter region. The absence of RBPJ led to an upregulation of miR-155.6. The expression of miR-155 was also significantly upregulated in many other types of human cancers including thyroid adenoma, breast cancer, colon cancer, cervical cancer, pancreatic cancer, and lung cancer[1,2]. More recently, Hurtado et al. identified a small-molecule inhibitor of the RBPJ protein RIN1, which disrupts RBPJ function as both a transcription activator and repressor; it remains to be determined to what extent RIN1 works in cancer therapy[3].