SMARCD3 (BAF60C) is a key subunit of the SWI/SNF chr7 remodeling complex that regulates gene expression through ATP-dependent chr7 remodeling 1. The protein plays critical roles in neural development, functioning as part of both neural progenitor-specific (npBAF) and neuron-specific (nBAF) chr7 remodeling complexes that control the transition from proliferating neural stem cells to postmitotic neurons 1. SMARCD3 orchestrates transcriptional programs by regulating cis-regulatory elements, including control of DAB1-mediated Reelin signaling essential for Purkinje cell migration 1. In vascular biology, SMARCD3 preserves vascular smooth muscle cell homeostasis by strengthening serum response factor association with coactivators and maintaining contractile phenotype, thereby preventing abdominal aortic aneurysm formation 2. However, SMARCD3 exhibits context-dependent tumor-promoting activities in multiple cancers. In pancreatic cancer, it acts as an epigenetic modulator controlling lipid and fatty acid metabolism programs associated with therapy resistance 3. The protein is amplified and enriched in cancer stem cells, contributing to aggressive tumor phenotypes 3. SMARCD3 also promotes medulloblastoma metastasis through hijacking neurodevelopmental programs 1 and facilitates colorectal cancer progression through cancer-associated fibroblast activation 4. These findings establish SMARCD3 as both a developmental regulator and potential therapeutic target in cancer.