The mammalian OS-9 (exhibiting ∼15% sequence identity with Yos9) was initially discovered in 1994 as one of the functionally unknown proteins whose genes were amplified in osteosarcoma (Su et al., 1994) and has a mammalian homolog (with ∼23% sequence identity) known as Erlectin or XTP3-B (XTP3-transactivated gene B) (Cruciat et al., 2006). The gene discussed is ERLEC1; the disease is osteosarcoma.