DLL4 and Granuloma: More recently, our group showed the first analysis of cell-mediated Th17-related pulmonary mycobacterial Ag-elicited granuloma formation in TLR9−/− mice and defined a role for TLR9 in the induction of both Notch ligand Dll4 and Th17 expression using both in vivo and in vitro approaches (Ito et al., 2009a).