To further study the function of USP27X, we used another RNA virus, vesicular stomatitis mutant virus (VSVΔM51-GFP) carrying a single amino acid deletion (Met51) in the matrix protein in VSV-GFP virus, and again observed increased abundance of Ifnb1, Ifit1 and Il6 mRNA in Usp27x knockdown cells following VSVΔM51-GFP infection compared with control cells (Fig 2F–2H). This evidence concerns the gene IFNB1 and infection.