PTGDR and mastitis: Particularly, abnormal DNA methylation around the STAT5-binding enhancer in the αS1-casein promoter negatively regulated αS1-casein synthesis in milk during lactation, which could be affected by foreign stimulus, such as mastitis and daily milking times (Platenburg et al., 1996; Vanselow et al., 2006; Nguyen et al., 2014).