Integrase interactor 1 (INI1/hSNF5) is a core component of the SWI/SNF chromatin remodeling complex that alters the structure of chromatin in order to facilitate DNA-dependent cellular processes like transcription, replication, and repair. Biallelic loss-of-function of INI1/hSNF5 leads to certain cancers, most frequently rhabdoid tumors, demonstrating that INI1/hSNF5 is a tumor suppressor gene. INI1/hSNF5 regulates several essential steps in the propagation of the HIV-1 virus within the host cell, particularly HIV-1 integration. The mode of function of INI1/hSNF5 is only beginning to be understood.