CD4 and myeloid sarcoma: In T cells, miRNAs are involved in most processes and haveimportant roles in T-cell activation and differentiation.14 A number of studies have profiled miRNAs in MS, and several miRNAs are nowemerging as important regulators, one such being miR-21.15 Expression of miR-21 in CD4+ T cells has been shown to negatively correlatewith DNA methylation at the CpGs in the MIR21 gene.16