ABCB1 and neuroblastoma: In addition, in neuroblastoma, amplification and upregulation of frizzled-1 Wnt receptor (FZD1) activate the Wnt/β-catenin pathway in chemoresistant cancer cells by nuclear β-catenin translocation and transactivation of Wnt target genes such as multidrug resistance gene (MDR1), which is known to mediate the resistance to chemotherapy [163].