miR-150-5p, one of the most highly expressed miRNAs in normal naïve CD4+ T-cells (see below), stands out among the many miRNAs that have been identified as deregulated by HTLV-1, as it was initially reported to be downregulated in HTLV-1-transformed cell lines and ATLL-derived cell lines but upregulated in ATLL samples compared to normal PBMC (19) and CD4+ T-cells (24). Here, CD4 is linked to adult T-cell leukemia/lymphoma.