Zwilch is the human homolog of the Drosophila Zwilch protein. The Drosophila Zwilch forms a complex with both ROD Rough Deal) and ZWINT (Zeste-White 10, also designated ZW10) proteins. This complex is important for chromosome segregation because it recruits cytoplasmic Dynein to the kinetochore and plays a crucial role in the spindle checkpoint. The role of Zwilch in complex is thought to be evolutionarily conserved because the human homologs of Zwilch, ZWINT and ROD coimmunoprecipitate in a human cell line called HeLa. The human Zwilch, ZWINT and ROD complex localizes to the kinetochores at prometaphase. Mutations were discovered in Zwilch, ZWINT and ROD during a screen for mutations in alleles encoding putative chromosome instability genes in cases of human colorectal cancer. These mutations may contribute in part to the chromosomal instability phenotype of colorectal tumor cells.