STAT3 and infection: Li et al. [72] mentioned that this miRNA is an important regulator in the infection from hepatitis C and B virus and Epstein-Barr virus; the authors found that miR-21-5p is important in maintaining the effector phase of Treg cells and that it is highly involved in the modulation of interferons (IFN), nuclear factor-κB (NF-κB) and signal transducer and activator of transcription (STAT3).