The immunohistochemical results were further confirmed by Western blot analysis (Figure 7A–C), which showed that silica (4w and 8w) increases the expressions of α-SMA by 3.11 and 3.13 fold compared with control group (4w and 8w), and that Ac-SDKP post-treatment and pre-treatment significantly attenuated the expression of α-SMA in rat lung with silicosis to 66.96% and 63.69%, respectively. This evidence concerns the gene ACTA1 and silicosis.