mRNA expression of molecules in the mTOR signalling pathway and immunohistochemical staining of mouse bone marrow (×400), nuclei were stained with 4′,6-diamidino-2-phenylindole (DAPI) reagents (blue). a mRNA expression of mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase (S6K1), Fanconi anaemia complementation group D2 (FANCD2), ataxia telangiectasia mutated gene (ATM) and checkpoint kinase (Chk2); b representative images of the expression of mTOR by immunohistochemistry (brown colour stain); c mTOR average optical density analyses; d representative images of the expression of FANCD2 by immunohistochemistry (brown colour stain); e FANCD2 average optical density analyses; f representative images of the expression of Chk2 by immunohistochemistry (brown colour stain); g Chk2 average optical density analyses. n = 6 for each group, * means p < 0.05, ** means p < 0.01, *** means p < 0.001, compared with the control group; & means p < 0.05, && means p < 0.01, &&& means p < 0.001, compared with the 160 PM2.5 group.