PCI-32765 inhibits FcγR signaling in monocytes. (a) Inhibition of Btk signaling in THP-1 cells. THP-1 cells were stimulated with IFN-γ and pretreated with PCI-32765 (1 μM or 0.1 μM) or vehicle and stimulated by cross-linking with human IgG and goat anti-human IgG in the presence of H2O2 and IFNγ. Cell lysates were subjected to western blot analysis and probed with the indicated antibodies. (b) Inhibition of calcium mobilization in THP-1 cells (upper panel) or human monocytes (lower panel) stimulated with cross-linked IgG as described in Materials and Methods.