Summary of miR-155 regulation and functions. Transcription of miR-155 is up-regulated by the transcription factors NF-κB, AP-1, Myb, and HoxA9 and inhibited by Stat3- and Akt-dependent pathways. miR-155 targets mRNAs encoding Ship1, Socs1, as well as other proteins. Inhibition of Ship1 and Socs1 by miR-155, which themselves normally inhibit inflammatory responses, leads to enhanced activation of proinflammatory pathways. Functionally speaking, miR-155 has been shown to promote myeloid development and function and play a positive role in the promotion of cancer and autoimmunity.