Fzd8 expression in bone cells. (A) qRT-PCR expression analysis for Wnt receptor-encoding genes using cDNA from various tissues and bone cells. Expression levels were normalized to Gapdh as indicated. Error bars represent mean ± SD (n = 4). (B) qRT-PCR expression analysis for Fzd8 and Fzd9 during the course of osteoclast and osteoblast differentiation. Error bars represent mean ± SD (n = 4). Asterisks indicate statistically significant differences compared with the earliest stage of differentiation. (C) Immunohistochemistry on human bone sections demonstrates the presence of FZD8 in osteoblasts (top) and osteoclasts (bottom). Bars, 25 µm.