FcγRI, synonymously also referred to CD64, is a membrane spanning protein of 72 kDa and belongs to the immunoglobulin (Ig) supergene family. It has three extracellular Ig-like domains and is the only receptor that can efficiently bind monomeric IgG and aggregated IgG17. Hence, FcγRI is known to functions as a high-affinity Fcγ receptor where exists other two members FcγRII (CD32) and FcγRIII (CD16), but with low affinity. In humans, FcγRI is constitutively expressed on monocytes/macrophages, myeloid precursors, as well as follicular dendritic cells and its expression can also be induced on polymorphonuclear neutrophils via IFN-γ or G-CSF. Now, FcγRI is considered a great monocyte/macrophage-associated marker, normally used in flow cytometry (FCM) to identify leukemias with myelomonocytic differentiation. The epidermal growth factor receptor (EGFR) is over-expressed in various human epithelial tumors usually due to the gene amplification. EGFR gene amplification in tumors frequently contain its rearrangements and among them, the most common extracellular domain mutation is receptor variant III, EGFRvIII (also known as de2-7EGFR or DEGFR). The molecular mass of EGFRvIII is approximately 145 kDa and this genetic change of tumor-specific mutation results from a deletion of 267 amino acids spanning exons 2-7 of the EGFR gene. These consequences make the variant EGFRvIII incapable of binding known ligand. It is expressed in a majority of patients with glioblastoma multiforme. And the evidence shows aberrant EGFRvIII signaling is important for driving tumor progression.