Validation of miRNA expression levels by qRT-PCR. The amount of miRNA-181a, -181b, -382, -222, -221, -15a, and -16 in MM samples compared with normal controls, evaluated by qRT-PCR (□) and microbead miRNA profiling (■). Results are expressed as fold change of the miRNA expression in bone marrow (BM) MM CD138⁺ cells with respect to average miRNA expression from 4 normal donor BM CD138⁺ cells. qRT-PCR data were obtained using the ΔΔCt method, with normalization to the reference RNU6B microRNA. Bars represent SDs.