IFNB1 and viral infectious disease: STAT1 mRNA levels were slightly increased in wild-type MEFs treated with IFNβ (Figure S2C), which is consistent with studies demonstrating that STAT1 expression is induced in fibosarcoma cell lines treated with IFNα or β [12] and in splenic leukocytes where STAT1 levels were increased following virus infection in a type I IFN-dependent manner [11].