The specificity of cetuximab reaction with TAF in tumor specimens was also supported by the finding that the isotype-matched antibody rituximab (anti-CD20 humanized antibody) did not stain TAF or FB in situ (Figures 4E,L,Q) and that cultured TAF or FB did not express FCγRI, FCγRII, and FCγRIII (Figure 3A, CD64, CD32, and CD16). The gene discussed is FCGR2A; the disease is neoplasm.