Effect of multi-walled carbon nanotube (MWCNT) inhalation on pulmonary inflammatory protein levels at different time points after exposure. Chemokine (C-X-C motif) ligand 2 (Cxcl2), chemokine (C-C motif) ligand 7 (Ccl7), and chemokine (C-C motif) ligand 9 (Ccl9) were measured from the first fraction of collected bronchoalveolar lavage fluid. Data are expressed as percent (%) change from respective sham (dashed line – 100%). Measurements were made from all doses at 0 d and the high and middle dose at 28 d since no effect was observed in the low dose at 0 d. 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.