The human chromosomal region 11p15 has undergone intense analysis because of its association with various malignancies. In particular, the band 11p15.5 contains genes associated with Wilms tumor, Beckwith-Weidemann syndrome, rhabdomyosarcoma, adrenocortical carcinoma, and lung, ovarian, and breast cancer. One such gene, GOK (Stim 1), was identified near the 5' end of the ribonucleotide reductase subunit 1 gene. Examination of the GOK primary amino acid sequence indicates that it is a typical transmembrane protein with an extracellular N-terminal domain and a cytosolic C-terminal domain. The protein is highly hydrophobic with only a short region of hydrophobicity that likely represents the transmembrane region. The C-terminal portion of GOK shares some small regions of homology with myosin (20% identity). This region of GOK consists of α-helices and is thought to adopt a coiled-coil conformation. Although GOK expression has no effect on the growth of certain breast cancer cell lines, it induces death in rhabdomyosarcoma cells. Thus, it is thought to be a recessive tumor suppressor in muscle cells, possibly by functioning as a receptor connected to an apoptotic signaling pathway.