Similarly, trastuzumab IgE, cetuximab IgE, anti‐PSA IgE, and MOv18 IgE activated RBL SX‐38 rat basophilic leukaemia cells when cross‐linked with anti‐IgE antibody engaged with multimeric antigen, or when incubated with target cells overexpressing specific tumour‐associated antigen 84, 99, 100, 102. The gene discussed is IGHE; the disease is leukemia.