MAPK-induced Ser727 phosphorylation promotes SUMOylation of STAT1.

STAT1 (signal transducer and activator of transcription 1) is a critical mediator of IFN-gamma (interferon-gamma)-induced gene responses, and its function is regulated through phosphorylation of Tyr701 and Ser727. MAPK (mitogen-activated protein kinase) pathways mediate phosphorylation of Ser727 in response to microbial infections, stress stimuli and growth factors. Recently, STAT1 was found to become modified by PIAS (protein inhibitor of activated STAT)-mediated SUMO-1 (small ubiquitin-related modifier-1) conjugation at Lys703, but the regulation of this modification is largely unknown.