MCRS1 (microspherule protein 1) is a multifunctional regulatory protein that plays critical roles in transcriptional regulation, cell cycle control, and cellular signaling pathways. As a component of chr12 remodeling complexes including NSL and INO80, MCRS1 modulates histone acetylation and gene expression 1. The protein regulates bile acid transporter gene expression through histone acetylation mechanisms, with hepatocyte-specific MCRS1 loss leading to cirrhosis development in mice 1. In cancer biology, MCRS1 demonstrates context-dependent functions: it enhances MHC-I expression and sensitizes pancreatic cancer cells to T cell-mediated immunity and α-PD-1 therapy 2, while also being associated with immunosuppressive microenvironments in hepatocellular carcinoma through recruitment of M2 macrophages 3. MCRS1 is essential for mTORC1 signaling by maintaining RHEB at lysosome surfaces in an amino acid-dependent manner, preventing its interaction with the inhibitor TSC2 4. Additionally, MCRS1 localizes to centriolar satellites and is required for dynein-dependent cargo transport, primary cilium formation, and proper brain and eye development in zebrafish 5. The protein also plays important roles in embryonic development, with involvement in H3K9me3 reprogramming during somatic cell nuclear transfer 6.