H&E staining of the contralateral non-tumor-bearing lungs was also performed to verify the protective effect of Rac1 inhibition on RILI, and results demonstrated that 1 week after radiation, the thickness of alveolar septum in the NC + NSC group and the SH + NSC group were significantly smaller than those of the NC + PBS group and the SH + PBS group, respectively (P < 0.01 and P < 0.001, respectively) (Fig. 6L, M), similar results were seen on 2 weeks after radiation (both P < 0.001) (Fig. 6N, O). This evidence concerns the gene RAC1 and neoplasm.