MIB1 (Mind bomb 1) is an E3 ubiquitin ligase that plays critical roles in NOTCH signaling, cancer progression, and cardiac development. The protein functions primarily by ubiquitinating NOTCH ligands like JAG1, which is essential for NOTCH pathway activation 1. The third RING domain and adjacent coiled coil region (ccRING3) are responsible for MIB1's dimerization and ubiquitin transfer activity, representing the minimal functional unit for NOTCH signaling induction 1. In cardiac development, heterozygous MIB1 mutations cause left ventricular noncompaction (LVNC) and bicuspid aortic valve when combined with additional genetic modifiers, highlighting its role in NOTCH-dependent cardiac morphogenesis 2. MIB1 has dual roles in cancer, acting as both tumor suppressor and promoter depending on context. It promotes gastric cancer peritoneal metastasis by degrading DDX3X and enhancing epithelial-mesenchymal transition 3, while in colorectal cancer, it inhibits proliferation through transcriptional repression of FGFR1 and STAT1/P21 signaling 4. During adenoviral infection, MIB1 facilitates viral genome nuclear import by ubiquitinating viral protein V at the nuclear pore complex 5. Clinically, MIB1 expression serves as a proliferation marker in various tumors and correlates with cancer progression 67.