Cloning K4 and K5 VH genes into a mammalian cell expression vector containing the human IgG1constant domains’ gene, followed by co-transfection of NS0 myeloma cells with this construct and a vector that contains the original nimotuzumab kappa light chain gene, gave rise to cell lines producing the new mAbs K4 and K5. Here, KRT4 is linked to plasma cell myeloma.