Figure 7From: A PKC-SHP1 signaling axis desensitizes Fcγ receptor signaling by reducing the tyrosine phosphorylation of CBL and regulates FcγR mediated phagocytosisFcγR1 activates Rac. (A) The activation of total Rac and Rac2 was measured following FcγR1 stimulation in U937 cells (See Methods) using GST-PAK1_CRIB domain pull down assay. U937 cells were treated with PMA or PKC inhibitor (GF109203X) to determine the effect of PKC on Fcγ receptor desensitization. The protein bound to GST-PAK1-CRIB is resolved on SDS-PAGE and immunoblotted with antibody for total Rac. Same experiment was repeated and immunoblotted with antibody specific for Rac2. Lane 1, no stimulation; lane 2 & 3, preincubated with PMA (200 ng/ml) for 5 min. at 37°C followed by FcγR stimulation for 1 and 5 min. respectively, lane 4 & 5, cells were preincubated with GF 109203X (2.5 μM) for 15 min. on ice and then treated with PMA (200 ng/ml) for 1 & 5 min. followed by FcγR1 stimulations, lane 6 and 7, FcγR1 stimulation (alone) on Rac-GTP levels. The experiment was repeated three times. (B) Graphic representation of the signaling mechanism reported in the present study.Back to article page