FZD9 and osteosarcoma: Similarly, FZD9, which belongs to frizzled receptors (FZDs) family that are G protein-coupled receptors essential for WNT signaling pathway, was also found recently to be upregulated in a group of cancers including the highly aggressive astrocytoma as well as osteosarcoma, and its knockdown was shown to reduce cell proliferation and motility in hepatocellular as well as hepatoblastoma cell lines (30, 31).