Our lab focuses on studying the structural basis of essential RNA-protein complexes as well as chromatin modifiers that participate in epigenetic and transcriptional regulations involved in tumorigenesis. We have made very important research progresses using integrated structural methodologies of Cryo-electron microscopy, X-ray crystallography, Nuclear magnetic resonance and Cross-linking mass spectrometry. Our major scientific contributions include: (1) provided an unprecedented structural framework for the activation mechanism of MLL (Mixed Lineage Leukemia) methyltransferases and advances understanding of the multifaceted cellular functions of MLL and the pathogenic roles in MLL-related tumorigenesis. (2) uncovered the structural basis for the histone-crosstalk regulation of histone methyltransferase DOT1L by ubiquitylation of histone H2B lysine 120. (3) revealed the structural mechanisms of the tumor suppressor protein menin in different gene transcriptional regulations and also in the MLL-mediated tumorigenesis. (4) determined the atomic structure of an essential telomerase RNA-protein complex that reveals residues and structural features crucial for telomerase ribonucleoprotein assembly and offers new opportunities for telomerase-targeted drug design. (5) determined several complex structures of chromatin modifiers associated with nucleosomes and demonstrated their functional mechanism. Our research work has been published in top journals such as Nature, Nature Structural & Molecular Biology, Cell Research and Cancer Research.