It was demonstrated over 25 years ago that malignant MM precursor cells exist in the peripheral blood and can be induced to proliferate and differentiate into clonal MM PC with interleukin-3 (IL-3) and IL-6 treatment.15 Given the increasing evidence suggesting a role for MELK in cancer stem cells,3 we sought to determine the effects of OTS167 on the outgrowth and differentiation of presumptive myeloma stem cells into MM PC. The gene discussed is IL3; the disease is plasma cell myeloma.