IL4 can signal through type I and type II receptor complexes, which share a common gamma chain (?c). The type I receptor contains in addition to the ? chain an IL4Ra subunit, whereas the type II receptor contains the IL13Ra. The secreted extracellular domain of IL4Ra, called sIL4Ra, binds IL4 and antagonizes its activity. It plays an important role in regulating the differentiation of naive CD4+ T cells and class switching to IgG1 and IgE. Alternative Names: IL 4, soluble IL-4 receptor alpha protein, IL4, CD124 protein, IL-4, IL-4 protein, Interleukin 4R alpha protein, IL-4Ralpha protein, IL 4 protein