MELK gene expression analysis was performed on publically available data sets GSE5900,4 GSE2658 (refs 5, 6) and GSE6477 (ref. 7) and demonstrated significantly increased MELK mRNA expression in newly diagnosed MM PC (n=628) compared with either normal PC (nPC; n=37; P=0.0189), monoclonal gammopathy of undetermined significance (MGUS) CD138+ PC (n=65; P<0.0001), or PC from smoldering MM patients (n=36; P=0.0003; Figure 1a). Here, MELK is linked to monoclonal gammopathy.