PSMB1 and mastitis: 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.