FZD8 and cancer: Among these genes, FZD8, a receptor for activating canonical WNT/β-catenin signaling [26], and POU3F2, a target gene of the WNT/β-catenin pathway that has shown tumorigenic effect in cancer [27], were significantly downregulated in bortezomib-treated cells, suggesting that the WNT/β-catenin pathway might be an important target pathway by bortezomib in MM cells.