Effect of multi-walled carbon nanotube (MWCNT) inhalation on pulmonary inflammatory gene expression at different time points after exposure. Interleukin 6 (Il6), chemokine (C-C motif) ligand 2 (Ccl2; also referred to as monocyte chemotactic protein-1), and chemokine (C-X-C motif) ligand 2 (Cxcl2; also referred to as macrophage inflammatory protein 2-alpha) were measured. Data are expressed as percent (%) change from respective sham (dashed line – 100%). Data presented as high dose (gray bars), medium dose (pattern), and low dose (black bars). *p<0.05 vs. respective sham; #p<0.05 vs. other MWCNT depositions for a given time point only.