Frizzled 4 (FZD4) belongs to the frizzled receptors family. It is a receptor for Wnt proteins, which can activate both Wnt/β-catenin canonical and Wnt/Ca2+ non canonical pathways. FZD4 plays an important role in retinal vascularization by binding Norrin ligand, a Wnt-unrelated growth factor, and activating the β-catenin signaling pathway. In addition, dysregulation of FZD4 expression has been reported in different type of cancers.
A monoclonal antibody specifically binding to FZD4 with high affinity is being developed. Preclinical development for familial exudative vitreoretinopathy (FEVR) and cancers is ongoing.