One of the most well-studied mechanisms by which ATP-dependent chromatin remodeling can assume tumor suppressor functions comes from the rare childhood cancer MRT caused by biallelic inactivation of BAF47 (hSNF5, INI1) in virtually 100% of the tumors (61, 68). These tumors show a classic loss of heterozygosity in the tumor and hence are recessive tumor suppressors. Wilson and colleagues (69) have shown that the underlying mechanism is rooted in the ability of BAF complexes to regulate the placement and function of Polycomb repressive complexes. The conditional deletion of BAF47 in mice leads to T cell lymphomas with a short latency that is unprecedented for the deletion of a single gene (70). This short latency time recalls the fact that human rhabdoid sarcomas often occur in the first 2 years of life, an observation that indicates that the mouse model, even though yielding a different type of tumor, likely has a similar pathogenesis. BAF complexes in the mutant cells are unable to remove Polycomb complexes and their histone modification, H3K27Me3, from the Ink4a (Cdkn2a) locus, which normally suppresses proliferation (69). The
