CSN1S1 and Bovine mastitis: Investigating the involvement of epigenetic factors in bovine mastitis, the most common and costliest disease of dairy cattle, Vanselow et al. (2006) observed that a hypomethylated region of the upper promoter region of alpha S1 casein gene becomes remethylated (accompanied by shutdown of alpha S1 casein synthesis) following experimental challenge of the mammary gland with pathogenic Escherichia coli bacteria.