The INI-1 gene (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1) is a protein that in humans is encoded by the SMARCB1 gene. The protein encoded by this gene is part of a complex that relieves repressive chromatin structures, allowing the transcriptional machinery to access its targets more effectively. This gene has been found to be a tumor suppressor, which is often mutated or deleted in malignant rhabdoid tumors, epithelioid sarcoma, and some malignant peripheral nerve sheath (MPNST) tumors.