STAT1 and infection: Phosphorylation of STAT1 could be restored during infection with sarA mutant S. Typhimurium complemented with a sarA-expressing plasmid, and the heterologous expression of SarA in S. Typhi also increased levels of phosphorylated STAT1 (Fig. 6B), demonstrating that SarA is responsible for the sustained phosphorylation of STAT1 observed in S. Typhimurium-infected macrophages.