FZD4 and cancer: Previous studies show that ERG regulates the expression of frizzled class receptor 4 [43], E-cadherin [43], vimentin [43], ras homolog family member A [44], vascular endothelial growth factor receptor 2 [45], and zinc finger E-box binding homeobox 1/2 [46] during cancer metastasis and epithelial–mesenchymal transition process.