Following experimental infection of cows (different animals than those used for Western blotting analysis) with the bovine E. coli 1303 mammary pathogenic E. coli (MPEC) strain, IL-1beta, IL-6, IL-8, and CHI3L1 mRNA expression levels in these udder quarters were compared with those from uninfected quarters from the same cows (internal controls) and quarters of uninfected cows (external controls, data not shown). This evidence concerns the gene IL6 and infection.