ERBB2 and neoplasm: To specifically direct UniCAR-NK cells to the tumor-associated antigen ErbB2, we designed a target module termed 5FE, which reflects structure and molecular mass of an IgG molecule and encompasses an N-terminal scFv antibody domain derived from ErbB2-specific antibody FRP5 [24], linked via hinge, CH2 and CH3 domains of the human IgG4 Fc portion to a C-terminal E5B9 epitope (Fig. 2a, left).