Fig. 4.

LPS releases CD38 into the extracellular space through MMP-9 in J774 macrophage cells. (A) CD38 release by LPS treatment. J774 cells were treated with 100 ng/ml LPS for the indicated times. Cell-associated CD38 protein levels as well as culture supernatant CD38 were measured by Western blotting after immunoprecipitation. (B) MMP-9 inhibitor blocks LPS-induced CD38 release. J774 cells were treated with 100 ng/ml LPS for 24 h in the presence of 5 nM or 50 nM MMP-9 inhibitor. CD38 protein levels in the cell pellets were measured by Western blotting.