Targeted hNIS expression in myeloma cells with radioiodide uptake. A transcriptionally targeted lentivector coding for hNIS was generated as described in “Materials and methods.” (A) A single mRNA transcript under the control of the targeted promoter and enhancers is generated, coding for hNIS as well as neomycin phosphotransferase to allow selection of transduced cells. ARH-77 cells were transduced with the vector and selected in G418. (B) In vitro ¹²⁵I uptake studies were performed on untransduced as well as transduced cells in the presence and absence of potassium perchlorate. The cells transduced with the vector concentrate radioiodine 18-fold compared with controls. Error bars indicate SD.