PIAS1 and mastitis: In the promoter region of the PIAS1 gene (Figure 4), the methylation levels of CpG2 and CpG12 sites were higher in the mastitis group than in the healthy group, the methylation levels of other CpG sites were lower in the mastitis group, and the methylation level of the CpG15 site was significantly lower in the mastitis group (p < 0.01).