Receptor expression after electroporation is transient and typically declines after 48 hours becoming undetectable after 96 hours. Because the aim of NK cell therapy is not to induce durable immunity but to rapidly reduce tumor cell burden, and the infused NK cells are rejected by the host immune system after approximately 2 weeks of infusion, the transient nature of the expression should not significantly affect anti-tumor potential. Moreover, by using this strategy, safety concerns regarding insertional mutagenesis and long-term persistence of transduced residual T cells do not apply. In any case, we will minimize the number of residual T cells in the final product as much as possible by depleting the expanded product of T cells by using the CliniMACS device, and by limiting the number of T cells in the graft to <0.05 x 10^6/kg.