Fig. 3

CD180 signaling in human B cells. Upon CD180 engagement with anti-CD180, CD19 becomes phosphorylated and associates with CD180 in the membrane. Downstream signaling members Vav appear to be crucial for transducing CD180 signals. CD180 concomitantly activates mitogen activated protein kinases and Akt signaling in healthy B cells, both of which appear to contribute to the upregulation of costimulatory molecules and cell survival. CD180 also associates with the PIM-1L kinase at the cell surface, which, upon activation of CD180 with anti-CD180, results in increasing levels of BAD. B cells can also receive signals from CD40 and interleukin 4 (IL-4) receptors to promote proliferation and survival whilst CD40 activation may promote upregulation of PIM-1L