Interestingly, cyclin D1 expression (Supplementary Fig. 9A) and Akt phosphorylation (Supplementary Fig. 9B) were significantly lower in the Wnt1 knockdown groups, suggesting that Wnt/β-catenin signaling may positively regulate breast cancer growth through activation of the cyclin D1 and Akt signaling pathways (Supplementary Fig. 9C). Here, CCND1 is linked to breast cancer.