Fig. 1 shows the scatter plot of microarray signals from normal and mastitis tissue. The expression levels of many genes differed between groups. Microarray data analysis indicated that 79 genes associated with the TLR4/NF-kB signaling pathway were differentially expressed (P < 0.01) (Fig. 2). Comparison of the two groups revealed that 19 genes from the TLR4/NF-kB signaling pathway were up-regulated (≥2 fold), whereas, 29 genes were down-regulated in mastitis tissue (≥2 fold) (Table 2). Here, TLR4 is linked to mastitis.