Several studies reported contributions of miR-21 to T cell activation [6], Dendritic cells (DCs) differentiation through regulation of the Protease for programmed cell death4 (PDCD4) and the stromal antigen 2 (STAG2), and granulocyte activation [27] resulting in excessive inflammatory mediators and enormous cell death which augment the association of miR-21 to SLE activity [28]. This evidence concerns the gene PDCD4 and systemic lupus erythematosus.