Interleukin-4 (IL4) is one of the most studied Th2 cytokines of the immune system where it is mainly produced by activated T cells, mast cells, basophils, and eosinophils. On lymphocytes, IL4 activates the type I IL4 receptor (IL4R), consisting of the IL4Rα and common gamma (γc) chains, to promote differentiation, survival, and proliferation for clonal expansion .While most normal epithelial cells do not express IL4Rs, epithelial cancer cells including breast cancer cells upregulate the type II IL4R consisting of the IL4Rα and IL13 receptor α 1 (IL13Rα1) chains. Similar to immune functions, Il4/IL4R signaling may promote the survival and proliferation of cancer cells. In fact, IL4/IL4R signaling has been shown to increase survival via the upregulation of anti-apoptotic proteins (PED, cFLIP, BclxL and Bcl2) to promote human breast and colon tumor growth in nude mice.