Fig. 5. (A ) Western blot analysis of inducible nitric oxide synthase (iNOS) protein expression in lung tissue. Animals with acute lung injury received normal saline (control), endothelial cells, or autologous transplantation of endothelial progenitor cells (EPCs) 2 days after administration of endotoxin. (B ) Expression of iNOS was enhanced after induction of acute lung injury, whereas autologous transplantation of EPCs significantly down-regulated iNOS expression in the injury lung tissue. *P < 0.05, EPC versus control and endothelial cells groups; n = 6. Data are presented as mean ± SD. The relative density of bands quantified by scanning densitometry was analyzed using ANOVA followed by the Tukey post hoc test. Control = normal saline; EC = endothelial cells; EPC = endothelial progenitor cells.