Additionally, in terms of individual highly connected genes identified in the blue module, several genes such as BIRC3, PSMA6, PSMB1, PSMD12, PSMD14, PSMD7 (Brand et al., 2011; Loor et al., 2011), EIF2S1 (Appuhamy et al., 2011), PTPRC (Nicholas et al., 2003), and CD53 (Rinaldi et al., 2010) have been reported as important genes in mastitis development. This evidence concerns the gene PSMA6 and mastitis.